Subsequent Events (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.82	$ 0.35	$ 0.35	$ 0.35
Paid subsequent to year end [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.82
2012 Revolver [Member] | 2012 Revolver borrowing capacity [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount	$ 2,200.0				2,200.0
Common Stock [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared	Oct. 30, 2014	Aug. 08, 2014	May 30, 2014	Feb. 20, 2014
Dividends Payable, Date to be Paid	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Dividends Payable, Date of Record	Dec. 19, 2014	Sep. 19, 2014	Jun. 20, 2014	Mar. 20, 2014
Common Stock [Member] | Dividend Declared [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared					Feb. 12, 2015
Dividends Payable, Date to be Paid					Mar. 31, 2015
Dividends Payable, Date of Record					Mar. 20, 2015