Long-Term Indebtedness (Details) (USD $)	9 Months Ended				9 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013 JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Feb. 24, 2011 JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Sep. 30, 2013 Prudential Investment Management, Inc. [Member]	Sep. 30, 2013 Senior Promissory Notes [Member] Maximum [Member] Prudential Investment Management, Inc. [Member]	Sep. 30, 2013 Prime Rate [Member] JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Sep. 30, 2013 Prime Rate [Member] Maximum [Member] JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Sep. 30, 2013 LIBOR Plus [Member] JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Sep. 30, 2013 LIBOR Plus [Member] Minimum [Member] JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]	Sep. 30, 2013 LIBOR Plus [Member] Maximum [Member] JPMorgan Chase Bank, N.A. And Wells Fargo Bank, N.A. [Member]
Debt Instrument [Line Items]
Debt outstanding	$ 0	$ 0	$ 0				$ 0
Letter of credit					2,200,000
Line of credit expiration date					Jan. 01, 2016
Credit expiration date							Feb. 24, 2014
Maximum borrowings under line of credit					50,000,000
Potential increase in line of credit borrowing capacity						20,000,000
Minimum prime interest rate									2.50%
Interest rate									0.00%	0.80%	2.00%	2.00%	2.80%
Maturity period of Promissory Notes								12 years
Period after request is issued, by company, for interest payable rate to be determined by Prudential	5 days
Maximum leverage ratio	2.5
Remaining availability under the facilities	197,800,000				47,800,000		150,000,000
Cash and cash equivalents	52,873,000	32,584,000	9,939,000	6,584,000
Extension period	3 years
Increase in line of credit, amount	$ 135,452,000	$ 37,702,000			$ 25,000,000