Related Party Transactions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]
Rental expense for operating leases	$ 1,204	$ 1,205
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Office and covered garage space leased (in square feet)	49,586
Rental expense for operating leases	853	865
Members of Management [Member]
Related Party Transaction [Line Items]
Aggregate carrying value of investments in Gray	$ 908	$ 696
Members of Management [Member] | Class A common stock [Member]
Related Party Transaction [Line Items]
Shares of Gray common stock owned (in shares)	388,060	388,060
Members of Management [Member] | Common Stock [Member]
Related Party Transaction [Line Items]
Shares of Gray common stock owned (in shares)	106,000	106,000