Investments (Details) (USD $)	12 Months Ended				12 Months Ended		69 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2008	Dec. 31, 2013 Auction Rate Securities	Dec. 31, 2012 Auction Rate Securities	Dec. 31, 2013 Auction Rate Securities	Dec. 31, 2013 Auction Rate Securities Minimum	Dec. 31, 2013 Auction Rate Securities Maximum
Schedule of Available-for-sale Securities [Line Items]
Realized Investment Gains (Losses)	$ 300,000	$ 300,000	$ 400,000
Student loan portfolios pledged as collateral, term of loans								17 years	32 years
Auction rate securities				82,100,000
Auction rate securities settled during period							70,700,000
Unrealized gain on auction rate securities	$ (1,015,000)	$ 1,529,000	$ 1,167,000		$ 700,000	$ 1,600,000