CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance at beginning of period at Dec. 31, 2013	$ 2,204,602	$ 42,201	$ (167,983)	$ 710,940	$ (8,361)	$ 1,627,805
Balance (in shares) at Dec. 31, 2013		422,015,000	5,618,000
Increase (Decrease) in Stockholders' Equity
Net income (loss)	104,468					104,468
Stock amortization and vesting	958	$ 91		867
Stock-based compensation	(1,375)			(1,375)
Stock amortization and vesting (in shares)		900,000
Purchase of treasury stock	$ (138,852)		$ (138,852)
Purchase of treasury stock (in shares)	4,300,000		4,275,000
Cash dividends at $0.08, $0.08 and $0.06 per share for the year ended December 31, 2015, 2014 and 2013, respectively	$ (33,278)					(33,278)
Other comprehensive income (loss)	6,210				6,210
Balance at end of period at Dec. 31, 2014	2,142,733	$ 42,292	$ (306,835)	710,432	(2,151)	1,698,995
Balance (in shares) at Dec. 31, 2014		422,915,000	9,893,000
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(113,891)					(113,891)
Exercise of stock appreciation rights	(942)	$ 4		(946)
Exercise of stock appreciation rights (in shares)		40,000
Stock amortization and vesting	$ 12,592	$ 81		12,511
Stock amortization and vesting (in shares)		814,000
Purchase of treasury stock (in shares)	0
Cash dividends at $0.08, $0.08 and $0.06 per share for the year ended December 31, 2015, 2014 and 2013, respectively	$ (33,090)					(33,090)
Other comprehensive income (loss)	1,786				1,786
Balance at end of period at Dec. 31, 2015	2,009,188	$ 42,377	$ (306,835)	721,997	(365)	1,552,014
Balance (in shares) at Dec. 31, 2015		423,769,000	9,893,000
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(417,124)					(417,124)
Issuance of common stock (in shares)		50,600,000
Issuance of common stock	995,289	$ 5,060		990,229
Exercise of stock appreciation rights	(198)	$ 3		(201)
Exercise of stock appreciation rights (in shares)		28,000
Stock amortization and vesting	16,931	$ 64		16,867
Sale of stock held in rabbi trust	544			544
Stock-based compensation	$ (2,126)			(2,126)
Stock amortization and vesting (in shares)		646,000
Purchase of treasury stock (in shares)	0
Cash dividends at $0.08, $0.08 and $0.06 per share for the year ended December 31, 2015, 2014 and 2013, respectively	$ (36,187)					(36,187)
Other comprehensive income (loss)	1,350				1,350
Balance at end of period at Dec. 31, 2016	$ 2,567,667	$ 47,504	$ (306,835)	$ 1,727,310	$ 985	$ 1,098,703
Balance (in shares) at Dec. 31, 2016		475,043,000	9,893,000