Earnings Per Share and Shareholders' Equity Transactions (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions			3 Months Ended												12 Months Ended
	Jan. 02, 2019	Dec. 30, 2018	Dec. 31, 2018		Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 29, 2018	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Antidilutive securities excluded from calculation of earnings per share															0.3		0.4	0.6
Repurchases common stock, shares																0.5
Repurchases common stock, value																$ 57,700,000
Repurchases of common stock under program, shares																14.9
Repurchases of common stock under program, value																$ 811,200,000
Special dividend declared per share		$ 4.75	$ 5.35	[1]	$ 0.54		$ 0.54		$ 0.54		$ 0.54	$ 0.50	$ 0.50	$ 0.50
Special dividend, declared date		Dec. 30, 2018
Special dividend, paid date		Jan. 25, 2019
Liabilities held for dividends payable			$ 193,400,000												$ 193,400,000
Subsequent Event [Member]
Class Of Stock [Line Items]
Initial delivery of shares of common stock received	1.8
Amount paid by company	$ 250,000,000
Accelerated Share Repurchase Agreement [Member]
Class Of Stock [Line Items]
Repurchases common stock, available for repurchases			$ 600,000,000												$ 600,000,000
Accelerated Share Repurchase Agreement [Member] | Subsequent Event [Member]
Class Of Stock [Line Items]
Shares repurchased under repurchase agreement, percentage	80.00%
Maximum [Member]
Class Of Stock [Line Items]
Repurchases common stock, authorized																$ 900,000,000
Maximum [Member] | Accelerated Share Repurchase Agreement [Member]
Class Of Stock [Line Items]
Repurchases common stock, authorized		$ 600,000,000

[1] As a result of the sale of Chaucer, (see Note 2 – “Discontinued Operations”), on December 30, 2018 the Board of Directors declared a special dividend of $4.75 per share (see Note 12 – “Earnings Per Share and Shareholders’ Equity Transactions”).