Capital Lease (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Component of Operating Other Cost and Expense [Line Items]
Lease term	11 years
Base rent per square foot (in dollars per square foot)	$ 18
Lease expense	$ 1,100,000	$ 1,100,000	$ 1,100,000	$ 1,100,000
Accumulated amortization on the leased property	3,800,000	3,500,000
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2013	1,160,000
2014	1,080,000
2015	1,080,000
2016	1,080,000
2017	1,080,000
Thereafter	6,480,000
Total minimum obligations	11,960,000
Interest	7,006,000
Present value of net obligations	4,954,000
Future sublease rentals	1,300,000
Term of capital lease sublease rentals	11 years
Estimated annual operating expenses to be borne by the Company	$ 825,000