Share repurchases (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended	4 Months Ended	9 Months Ended
	Nov. 04, 2019	Sep. 30, 2019	Nov. 04, 2019	Sep. 30, 2019	Nov. 06, 2019	Jul. 17, 2019
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)		30,592		32,652
Value of treasury stock acquired		$ 1,747,968		$ 1,860,157
Treasury stock acquired, average cost per share		$ 57.14		$ 56.97
Stock Repurchase Program, Authorized Amount						$ 2,000,000
Terminated Remaining Prior Share Repurchases Authorized, Amount						$ 1,005,605
Tender Offer
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)		21,802		21,802
Value of treasury stock acquired		$ 1,233,886		$ 1,233,886
Treasury stock acquired, average cost per share		$ 56.60		$ 56.60
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)	4,283		30,661
Value of treasury stock acquired	$ 245,544		$ 1,753,627
Treasury stock acquired, average cost per share	$ 57.32
Stock Repurchase Program, Authorized Amount	$ 2,000,000		2,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 2,000,000
Terminated Remaining Prior Share Repurchases Authorized, Amount	$ 246,373		$ 246,373