Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net Income (Loss) Attributable to Parent [Abstract]
Net income attributable to common stockholders	$ 79,323	$ 81,988
After tax interest on convertible debt	0	15
Net income — diluted	$ 79,323	$ 82,003
Weighted average shares (denominator):
Weighted average shares — basic	(181,696)	(185,130)
Convertible debt	0	121
Weighted average shares — diluted	185,317	189,923
Net income attributable to common stockholders, basic	$ 0.44	$ 0.44
Net income attributable to common stockholders, diluted	$ 0.43	$ 0.43
Equity Option [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options	3,562	4,522
Restricted Stock Units (RSUs) [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options	59	150
Equity Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	577
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	37	0