v3.7.0.1
ACCUMULATED OTHER COMPREHENSIVE INCOME - Change in AOCI by component (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Changes in accumulated other comprehensive income      
Balance at the beginning of the period $ 1,538,703 $ 1,512,732 $ 1,507,470
Other comprehensive income (loss), net of tax (5,355) (10,040) (11,360)
Balance at the end of the period 2,009,654 1,538,703 1,512,732
Accumulated Other Comprehensive Income (Loss)      
Changes in accumulated other comprehensive income      
Balance at the beginning of the period 2,804 12,844 24,204
Other comprehensive income (loss) before reclassifications (3,601) 535  
Amounts reclassified from accumulated other comprehensive income (1,754) (10,575)  
Other comprehensive income (loss), net of tax (5,355) (10,040) (11,360)
Balance at the end of the period (2,551) 2,804 12,844
Foreign Currency      
Changes in accumulated other comprehensive income      
Balance at the beginning of the period 2,101 729  
Other comprehensive income (loss) before reclassifications (3,881) 1,372 978
Other comprehensive income (loss), net of tax (3,881) 1,372  
Balance at the end of the period (1,780) 2,101 729
Pension and Other Benefits      
Changes in accumulated other comprehensive income      
Balance at the beginning of the period (3,289) 6,675  
Other comprehensive income (loss) before reclassifications   912  
Amounts reclassified from accumulated other comprehensive income (280) (10,876)  
Other comprehensive income (loss), net of tax (280) (9,964)  
Balance at the end of the period (3,569) (3,289) 6,675
Unrealized Net Gain on Marketable Securities      
Changes in accumulated other comprehensive income      
Balance at the beginning of the period 1,465 2,677  
Other comprehensive income (loss) before reclassifications 589 (1,056) 2,627
Amounts reclassified from accumulated other comprehensive income (1,816) (156) (31)
Other comprehensive income (loss), net of tax (1,227) (1,212)  
Balance at the end of the period 238 1,465 2,677
Unrealized Net Gain from Equity Method Investees' Cash Flow Hedge      
Changes in accumulated other comprehensive income      
Balance at the beginning of the period 2,527 2,763  
Other comprehensive income (loss) before reclassifications (309) (693) (59)
Amounts reclassified from accumulated other comprehensive income 342 457 528
Other comprehensive income (loss), net of tax 33 (236)  
Balance at the end of the period $ 2,560 $ 2,527 $ 2,763