Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended				1 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended
	Jun. 16, 2014	May 02, 2014	Mar. 24, 2014	Feb. 07, 2014	May 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jul. 31, 2014 Subsequent Event [Member]	Jun. 26, 2014 Common Stock [Member]
Dividends Payable [Line Items]
Stock split ratio											2
Cash dividend per common share (in dollars per share)		$ 0.11		$ 0.11						$ 0.11
Dividend declared and paid, common shares	$ 2.5		$ 2.5					$ 5.1	$ 2.2
Stock repurchase plan, authorized increase					30.0
Common stock available for future share repurchases, amount					2.3			25.7
Common stock repurchased, number of shares repurchased						600	11,004	83,200	155,218
Common stock repurchased, average price per share (in dollars per share)						$ 36.28	$ 28.74	$ 36.18	$ 24.78
Common stock repurchased, total repurchase costs						$ 0	$ 0.3	$ 3.0	$ 3.8