Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Stock-Based Compensation [Abstract]
Shares available for issuance under the 2011 Plan (in shares)	4,055,643
Stock options, granted (in shares)	545,085
Stock options, weighted average exercise price (in dollars per share)	$ 42.44
Stock options, vesting period (in years)	4Y
Stock options, expiration period (in years)	10Y
Stock options, weighted average grant date fair value (in dollars per share)	$ 7.93
Assumptions used in Black-Scholes model
Risk-free interest rate (in hundredths)	0.92%
Expected life (in years)	6
Stock volatility (in hundredths)	23.30%
Dividend yield (in hundredths)	1.70%
Number of shares of common stock per PVS award (in shares)	1
PVS payout, Minimum (in hundredths)	0.00%
PVS payout, Maximum (in hundredths)	200.00%
Granted, PVS awards (in shares)	101,857
Grant date fair value, PVS awards (in dollars per share)	$ 42.44
Stock-based compensation expense	$ 3.2	$ 3.3