Stockholders' Equity (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2018	Feb. 29, 2016
Class of Stock [Line Items]
Amount of common stock repurchases authorized					$ 1,100,000	$ 1,000,000
Stock repurchase authorized amount increase	$ 416,700
Remaining amount available for future purchases of shares under approved repurchase program.	$ 750,000	$ 571,900
Value of shares repurchased during period		$ 193,588	$ 334,519	$ 750,000
Common Stock
Class of Stock [Line Items]
Repurchases of common stock (in shares)		2.0	4.0	10.2
Value of shares repurchased during period		$ 193,600	$ 334,500	$ 750,000