Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under the 2011 Plan (in shares)	1,671,148
Stock options, granted (in shares)	573,236
Stock options, weighted average exercise price (in dollars per share)	$ 59.59
Stock options, weighted average grant date fair value (in dollars per share)	$ 11.53
Assumptions used in Black-Scholes model
Risk-free interest rate (in hundredths)	1.35%
Expected life (in years)	5 years 11 months
Stock volatility (in hundredths)	20.30%
Dividend yield (in hundredths)	0.90%
Stock-based compensation expense	$ 4.6	$ 5.3
Performance Vesting Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	107,303
Grant date fair value (in dollars per share)	$ 59.59
Performance period	3 years
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%