Fair Value Measurements - Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Line Items]
Unrealized gains on the investments after-tax	$ 429,000	$ 275,000
Money market funds
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	118,000	10,177,000
Unrealized gains on the investments	0	0
Other mutual funds
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	2,023,000	1,239,000
Unrealized gains on the investments	700,000	450,000
Unrealized gains on the investments after-tax	429,000	275,000
Fair Value, Measurements, Recurring
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	$ 2,141,000	$ 11,416,000