Credit Facility (Details) (USD $) In Millions, unless otherwise specified		1 Months Ended	9 Months Ended			9 Months Ended	0 Months Ended
	Oct. 31, 2008 Credit facility	Sep. 30, 2012 Revolving Line of Credit	Dec. 31, 2013 Revolving Line of Credit	Mar. 31, 2013 Revolving Line of Credit	Oct. 31, 2008 Revolving Line of Credit	Dec. 31, 2013 Revolving Line of Credit Maximum	Oct. 31, 2008 Bank Term Note
Revolving Line of Credit
Maximum borrowing capacity	$ 19.5				$ 12.0
Principal amount							7.5
Term of debt instrument		2 years					48 months
Prime rate at the end of the period (as a percent)			3.25%
Monthly interest rate basis						prime rate
Basis points added to reference rate (as a percent)						0.25%
Unused line fee (as a percent)			0.25%
Amount outstanding			$ 0	$ 0