Stock Repurchases Tender Offer (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	2 Months Ended	12 Months Ended
	Feb. 20, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 11, 2018
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 110,001
Repurchase of common stock (in shares)		41,020	16,844	12,967
Value of treasury stock acquired		$ 2,402,475	$ 1,153,511	$ 810,949
Treasury stock acquired, average cost per share		$ 58.57	$ 68.48	$ 62.54
Tender Offer
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)		21,802	0	0
Value of treasury stock acquired		$ 1,234,154	$ 0	$ 0
Treasury stock acquired, average cost per share		$ 56.61	$ 0	$ 0
Treasury Stock, Shares Repurchases, Table Footnotes:
Treasury Stock Acquired, Average Cost Per Share, Clearing Price		$ 56.50
Share Repurchase Fees And Expenses		$ 2,343
Open Market Purchases
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)		19,218	16,844	12,967
Value of treasury stock acquired		$ 1,168,321	$ 1,153,511	$ 810,949
Treasury stock acquired, average cost per share		$ 60.79	$ 68.48	$ 62.54
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,681,701
Repurchase of common stock (in shares)	291
Value of treasury stock acquired	$ 21,794
Treasury stock acquired, average cost per share	$ 74.92