Amended and Restated Senior Credit Agreement (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jan. 17, 2013 Revolving Credit Facility [Member] Amended and Restated Senior Credit Agreement [Member]	Jun. 30, 2013 LIBOR [Member] 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	$ 0	$ 0	$ 263,000	$ 0	$ 300,000
Basis spread on variable rate							1.50%	0.50%	1.00%	0.50%
Interest rate at period end						1.70%