Common Stock Repurchase Plan (Narrative) (Details) - USD ($)			6 Months Ended		23 Months Ended
	Oct. 30, 2017	Jul. 29, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jul. 31, 2018
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, repurchased cost			$ 105,000,000	$ 70,900,000
Common Stock [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, expiration date		Jul. 31, 2018
Shares repurchase program, shares repurchased			1,785,816	1,659,452	4,700,000
Shares repurchase program, repurchased cost			$ 105,000,000		$ 229,200,000
Shares repurchase program, average price per share			$ 58.80		$ 48.33
Stock repurchase program, additional authorized amount	$ 250,000,000
Shares repurchase program, extended expiration date	Oct. 31, 2020
Common Stock [Member] | Subsequent Event [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, authorized amount						$ 700,000,000
Stock repurchase program, additional authorized amount						$ 300,000,000
Common Stock [Member] | Maximum [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, authorized amount		$ 150,000,000