CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive loss	Retained earnings (deficit)
Balance, beginning of year at Dec. 31, 2012		$ 205,047	$ 1,135,296	$ (104,959)	$ (48,163)	$ (990,281)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance		135,000	528,335
Net income (loss)	$ (49,848)					(49,848)
Net common stock issued under share-based compensation plans		0	0
Reissuance of treasury stock, net			(7,892)	40,524		(34,488)
Tax benefit from share-based compensation			0
Equity compensation			5,530
Other comprehensive income (loss)	(69,563)				(69,563)
Balance, end of year at Dec. 31, 2013	744,538	340,047	1,661,269	(64,435)	(117,726)	(1,074,617)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance		0	0
Net income (loss)	251,949					251,949
Net common stock issued under share-based compensation plans		0	0
Reissuance of treasury stock, net			(6,680)	31,498		(29,790)
Tax benefit from share-based compensation			0
Equity compensation			9,003
Other comprehensive income (loss)	36,385				36,385
Balance, end of year at Dec. 31, 2014	1,036,903	340,047	1,663,592	(32,937)	(81,341)	(852,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance		0	0
Net income (loss)	1,172,000					1,172,000
Net common stock issued under share-based compensation plans		50	(478)
Reissuance of treasury stock, net			(6,894)	29,575		(29,495)
Tax benefit from share-based compensation			2,116
Equity compensation			11,902
Other comprehensive income (loss)	20,461				20,461
Balance, end of year at Dec. 31, 2015	$ 2,236,140	$ 340,097	$ 1,670,238	$ (3,362)	$ (60,880)	$ 290,047