Condensed Consolidated Statements of Comprehensive Income (Loss) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net (Loss) Income	$ (161,563)	$ (3,265)	$ (150,470)	$ 33,152
Change in unrecognized benefit plan losses arising during the period, net of taxes of $2,367 and $(1,737) for the three and six months ended June 30, 2016 and June 30, 2015, respectively	3,671	(2,694)	3,671	(2,694)
Adjustment for previously unrecognized benefit plan gains and losses included in net income, net of taxes of $(20) and $8 for the three months ended June 30, 2016 and June 30, 2015, respectively, and $(57) and $5 for the six months ended June 30, 2016 and June 30, 2015, respectively	(30)	12	(88)	7
Change in unrecognized benefit plan gains and losses, net of taxes	3,641	(2,682)	3,583	(2,687)
Change in unrealized holding gain arising during the period, net of taxes of $909 and $(583) for three months ended June 30, 2016 and June 30, 2015, respectively, and $685 and $(1,188) for the six months ended June 30, 2016 and June 30, 2015, respectively	1,346	(904)	998	(1,843)
Change in foreign currency translation adjustments, net of taxes of $(1,161) and $766 for the three months ended June 30, 2016 and June 30, 2015, respectively, and $(1,095) and $(407) for the six months ended June 30, 2016 and June 30, 2015, respectively	(4,176)	523	(133)	(4,868)
Other Comprehensive Income (Loss), net of taxes	811	(3,063)	4,448	(9,398)
Comprehensive (Loss) Income	$ (160,752)	$ (6,328)	$ (146,022)	$ 23,754