Stockholders' Equity - Narrative (Details) - USD ($) shares in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Nov. 30, 2018
Class of Stock [Line Items]
Stock repurchase program, authorized amount			$ 1,100,000,000.0
Repurchases of common stock	$ (34,872,000)	$ (19,785,000)
Amortization expense from capitalized stock-based compensation	$ 8,100,000	$ 5,600,000
Common Stock
Class of Stock [Line Items]
Shares repurchased during period (in shares)	0.5