Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock	Common Stock Cumulative Effect, Period of Adoption, Adjustment	Common Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjusted Balance	Restricted Stock [Member]
Stockholders' Equity Attributable to Parent	$ 2,013.9	$ (24.1)	$ 1,989.8	$ 1,049.3	$ 0.0	$ 1,049.3	$ 953.6	$ (24.1)	$ 929.5	$ (11.0)	$ 0.0	$ 11.0
Net income	161.2			0.0			161.2			0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 45.6			0.0			0.0			45.6
Stock Repurchased and Retired During Period, Shares	3,578,743
Common shares purchased and retired	$ (116.8)			(116.8)			0.0			0.0
Stock issued during period, new issues (in shares)	19,491
Stock issued during period, RSU (in shares)	332,085
Stock Issued During Period, Value, New Issues	$ 0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock compensation expense	1.1			1.1			0.0			0.0
Stock compensation expense	7.5			7.5			0.0			0.0			$ 7.5
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition	$ (128.6)			0.0			(128.6)			0.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	34,912
Dividends declared (in usd per share)	$ 2.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	111,539
Shares tendered in payment of option price and income tax withholding amounts, shares	26,124
Stockholders' Equity Attributable to Parent	$ 1,959.8			941.1			962.1			(56.6)
Common Stock, Value, Issued	0.0			0.0			0.0			0.0
Net income	192.1			0.0			192.1			0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (67.6)			0.0			0.0			(67.6)
Stock Repurchased and Retired During Period, Shares	128,171
Common shares purchased and retired	$ (5.4)			(5.4)			0.0			0.0
Stock issued during period, new issues (in shares)	19,081
Stock issued during period, RSU (in shares)	241,307
Stock Issued During Period, Value, New Issues	$ 0.0			0.0			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock compensation expense	0.4			0.4			0.0			0.0
Stock compensation expense	8.9			8.9			0.0			0.0			8.9
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition	$ (101.6)			0.0			(101.6)			0.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	73,044
Dividends declared (in usd per share)	$ 1.64
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	45,484
Shares tendered in payment of option price and income tax withholding amounts, shares	6,982
Stockholders' Equity Attributable to Parent	$ 1,986.6			945.0			1,052.6			(11.0)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(11.0)
Common Stock, Value, Issued	0.0			0.0			0.0			0.0
Net income	202.2			0.0			202.2			0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (466.1)			0.0			0.0			(466.1)
Stock Repurchased and Retired During Period, Shares	5,040,896
Common shares purchased and retired	$ (199.0)			(199.0)			0.0			0.0
Stock issued during period, new issues (in shares)	46,913,370
Stock issued during period, RSU (in shares)	458,177
Stock Issued During Period, Value, New Issues	$ 1,722.5			1,722.5			0.0			0.0
Non-vested common shares forfeited or canceled	0.0			0.0			0.0			0.0
Stock compensation expense	0.1			0.1			0.0			0.0
Stock compensation expense	9.6			9.6			0.0			0.0			$ 9.6
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition	$ (182.1)			0.0			(182.1)			0.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	106,891
Dividends declared (in usd per share)	$ 1.70
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	17,807
Shares tendered in payment of option price and income tax withholding amounts, shares	4,877
Stockholders' Equity Attributable to Parent	$ 3,073.8			2,478.2			1,072.7			(477.1)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(477.1)
Common Stock, Value, Issued	$ 0.0			$ 0.0			$ 0.0			$ 0.0