Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Income (Loss) Attributable to Parent [Abstract]
Net income attributable to common stockholders	$ 174,702	$ 47,445
After tax interest on convertible debt	12	12
Net income — diluted	$ 174,714	$ 47,457
Weighted average shares (denominator):
Weighted average shares — basic	(188,260)	(194,924)
Convertible debt	121	121
Weighted average shares — diluted	192,867	198,030
Net income attributable to common stockholders, basic	$ 0.93	$ 0.24
Net income attributable to common stockholders, diluted	$ 0.91	$ 0.24
Equity Option [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options	4,425	2,985
Restricted Stock Units (RSUs) [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options	61	0
Equity Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	898	1,886