CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Common stock held in treasury	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)
Beginning balance at Dec. 31, 2013	$ 2,414,452	$ 1,634	$ (3,637)	$ 1,959,636	$ 450,583	$ 6,236
Beginning balance Shares at Dec. 31, 2013		163,441,000
Issuance of common stock	398,607	$ 53	0	398,554	0	0
Issuance of common stock, shares		5,270,000
Stock-based compensation expense	42,834	$ 0	0	42,834	0	0
Common dividends declared ($0.16 per share for 2014, 2015 and $0.08 per share for 2016)	(26,610)	0	0	0	(26,610)	0
Treasury stock issuance	0	0	549	(549)	0	0
Other comprehensive income (loss)	(6,236)	0	0	0	0	(6,236)
Net (loss) income	634,382	0	0	0	634,382	0
Ending balance at Dec. 31, 2014	3,457,429	$ 1,687	(3,088)	2,400,475	1,058,355	0
Ending balance Shares at Dec. 31, 2014		168,711,000
Issuance of common stock	10,073	$ 6	0	10,067	0	0
Issuance of common stock, shares		665,000
Stock-based compensation expense	36,496	$ 0	0	36,496	0	0
Tax benefit related to stock-based compensation	(3,572)	0	0	(3,572)	0	0
Common dividends declared ($0.16 per share for 2014, 2015 and $0.08 per share for 2016)	(27,083)	0	0	0	(27,083)	0
Treasury stock issuance	0	0	843	(843)	0	0
Net (loss) income	(713,685)	0	0	0	(713,685)	0
Ending balance at Dec. 31, 2015	$ 2,759,658	$ 1,693	(2,245)	2,442,623	317,587	0
Ending balance Shares at Dec. 31, 2015	169,375,743	169,376,000
Issuance of common stock	$ 3,048,653	$ 778	0	3,047,875	0	0
Issuance of common stock, shares		77,799,000
Stock-based compensation expense	37,023	$ 0	0	37,023	0	0
Tax benefit related to stock-based compensation	(2,062)	0	0	(2,062)	0	0
Common dividends declared ($0.16 per share for 2014, 2015 and $0.08 per share for 2016)	(16,682)	0	0	0	(16,682)	0
Treasury stock issuance	0	0	1,036	(1,036)	0	0
Cumulative-effect adjustment from adoption of ASU 2016-09	103,166	0	0	0	103,166	0
Net (loss) income	(521,388)	0	0	0	(521,388)	0
Ending balance at Dec. 31, 2016	$ 5,408,368	$ 2,471	$ (1,209)	$ 5,524,423	$ (117,317)	$ 0
Ending balance Shares at Dec. 31, 2016	247,174,903	247,175,000