Amended and Restated Senior Credit Agreement (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Jan. 17, 2013 Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]	Jan. 17, 2013 LIBOR [Member] Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]	Jan. 17, 2013 Federal Funds Rate [Member] Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]	Jan. 17, 2013 Eurocurrency [Member] Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]	Jan. 17, 2013 Alternate Base Rate [Member] Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 350,000,000
Loss on early extinguishment of debt	$ 263,000	$ 0	$ 300,000
Basis spread on variable rate				1.50%	0.50%	1.00%	0.50%
Interest rate at period end				1.71%