Credit Facility (Details) (USD $)		1 Months Ended	12 Months Ended			12 Months Ended
	Apr. 17, 2012 Interest rate swap	Jan. 31, 2009 Credit facility	Dec. 31, 2012 Credit facility	Mar. 31, 2014 Credit facility	Mar. 31, 2013 Credit facility	Dec. 31, 2012 Credit facility Minimum	Dec. 31, 2012 Credit facility Maximum
Credit Facility
Maximum borrowing capacity			$ 85,000,000	$ 75,000,000	$ 80,000,000
Variable interest rate base			LIBOR
Percentage points added to the reference rate			2.00%			1.50%	2.25%
Outstanding borrowings			58,500,000
Weighted average interest rate on the amount outstanding (as a percent)			2.21%
Amount available for borrowing pursuant to the facility			26,500,000
Amount available for borrowing subject to the required quarterly debt covenant			5,637,000
Anticipated length of amended credit agreement						12 months
Converted amount of borrowings		$ 35,000,000
Fixed interest rate (as a percent)	1.74%
Margin points added to reference rate, low end of the range (as a percent)	1.50%
Margin points added to reference rate, high end of the range (as a percent)	2.25%