Share Repurchase Program (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended		9 Months Ended	1 Months Ended			2 Months Ended
	Jan. 31, 2014	Aug. 31, 2013	May 31, 2014	Jan. 31, 2014 Incremental authorization to share repurchase program [Member]	Mar. 31, 2014 Accelerated Share Repurchase Program [Member]	Feb. 28, 2014 Accelerated Share Repurchase Program [Member]	Mar. 31, 2014 Accelerated Share Repurchase Program [Member]
Share Repurchase Program [Line Items]
Shares repurchase authorized amount	$ 80.0	$ 40.0		$ 40.0		$ 40.0
Shares acquired through stock repurchase program			3.6		0	2.1
Purchase of treasury stock			69.4			40.0
Remaining amount authorized for repurchase through share repurchase program			$ 10.6
Final price paid per share							$ 19.13
Weighted-average price per share			$ 19.32