Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Income (Loss) Attributable to Parent [Abstract]
Net income attributable to common stockholders	$ 47,445	$ 61,375
After tax interest on convertible debt	12	12
Net income — diluted	$ 47,457	$ 61,387
Weighted average shares (denominator):
Weighted average shares — basic	(194,924)	(203,510)
Stock options	2,985	4,121
Convertible debt	121	121
Weighted average shares — diluted	198,030	207,752
Net income attributable to common stockholders, basic	$ 0.24	$ 0.30
Net income attributable to common stockholders, diluted	$ 0.24	$ 0.30
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,900	1,100