Stockholders' Equity - Narrative (Details) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Nov. 30, 2018
Class of Stock [Line Items]
Stock repurchase program, authorized amount					$ 1,100,000,000
Repurchases of common stock	$ (175,500,000)		$ (291,788,000)	$ (625,925,000)
Amortization expense from capitalized stock-based compensation	$ 7,500,000	$ 6,600,000	$ 22,900,000	$ 18,100,000
Common Stock
Class of Stock [Line Items]
Shares repurchased during period (in shares)	2.0		3.6