Liquidity (Details) (Credit Agreement Amendment, September 2014, USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
Credit Agreement Amendment, September 2014
Debt Instrument, Covenants [Abstract]
Maximum Total Leverage Ratio, September 30, 2014		5.25
Maximum Total Leverage Ratio, December 31, 2014		5.25
Maximum Total Leverage Ratio, March 31, 2015		5.00
Maximum Total Leverage Ratio, June 30, 2015		4.75
Maximum Total Leverage Ratio, September 30, 2015		4.50
Maximum Total Leverage Ratio, December 31, 2015		4.25
Maximum Total Leverage Ratio, March 31, 2016		4.00
Maximum Total Leverage Ratio, June 30, 2016		3.75
Maximum Total Leverage Ratio, September 30, 2016		3.75
Maximum Total Leverage Ratio, December 31, 2016		3.50
Maximum Total Leverage Ratio, March 31, 2017		3.25
Maximum Total Leverage Ratio, June 30, 2017		3.25
Maximum Total Leverage Ratio, September 30, 2017		3.25
Maximum Total Leverage Ratio, December 31, 2017 and thereafter		3.00
Outstanding exposure fee (percent)	0.25%
Outstanding exposure fee	$ 1.7
Total leverage ratio			4.94