• Filing Date: 2019-03-08
  • Form Type: 10-K
  • Description: Annual report
v3.10.0.1
Fair Value Measurements - Schedule of Fair Value Information for Financial Assets and Liabilities Carried on Balance Sheet (Detail) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Financial Assets:    
Limited partnership investments $ 32,293 $ 23,184
Estimate of Fair Value Measurement [Member]    
Financial Assets:    
Limited partnership investments 32,293 23,184
Financial Liabilities:    
Total long-term debt 266,383 240,212
Estimate of Fair Value Measurement [Member] | 3.875% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 89,824 90,827
Estimate of Fair Value Measurement [Member] | 4.25% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 145,617 124,444
Estimate of Fair Value Measurement [Member] | 3.95% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 9,128 9,227
Estimate of Fair Value Measurement [Member] | 4% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 7,788 7,894
Estimate of Fair Value Measurement [Member] | 3.75% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 8,001 7,820
Estimate of Fair Value Measurement [Member] | 4.55% Promissory note [Member]    
Financial Liabilities:    
Total long-term debt 6,025  
Estimate of Fair Value Measurement [Member] | (Level 2) [Member]    
Financial Liabilities:    
Total long-term debt 235,441 215,271
Estimate of Fair Value Measurement [Member] | (Level 2) [Member] | 3.875% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 89,824 90,827
Estimate of Fair Value Measurement [Member] | (Level 2) [Member] | 4.25% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 145,617 124,444
Estimate of Fair Value Measurement [Member] | (Level 3) [Member]    
Financial Assets:    
Limited partnership investments 32,293 23,184
Financial Liabilities:    
Total long-term debt 30,942 24,941
Estimate of Fair Value Measurement [Member] | (Level 3) [Member] | 3.95% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 9,128 9,227
Estimate of Fair Value Measurement [Member] | (Level 3) [Member] | 4% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 7,788 7,894
Estimate of Fair Value Measurement [Member] | (Level 3) [Member] | 3.75% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 8,001 7,820
Estimate of Fair Value Measurement [Member] | (Level 3) [Member] | 4.55% Promissory note [Member]    
Financial Liabilities:    
Total long-term debt 6,025  
Carrying Value [Member]    
Financial Assets:    
Limited partnership investments 32,293 23,184
Financial Liabilities:    
Total long-term debt 250,095 237,835
Carrying Value [Member] | 3.875% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 89,181 85,436
Carrying Value [Member] | 4.25% Convertible Senior Notes [Member]    
Financial Liabilities:    
Total long-term debt 130,120 126,454
Carrying Value [Member] | 3.95% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 9,077 9,270
Carrying Value [Member] | 4% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 7,732 8,206
Carrying Value [Member] | 3.75% Promissory Note [Member]    
Financial Liabilities:    
Total long-term debt 8,159 $ 8,469
Carrying Value [Member] | 4.55% Promissory note [Member]    
Financial Liabilities:    
Total long-term debt $ 5,826