Fair Value Measurements - Narrative (Details) (USD $)			3 Months Ended			12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Money market funds	Mar. 31, 2013 Money market funds	Mar. 31, 2014 Other mutual funds	Dec. 31, 2013 Other mutual funds	Mar. 31, 2014 Fair Value, Measurements, Recurring	Mar. 31, 2013 Fair Value, Measurements, Recurring	Mar. 31, 2014 Fair Value, Measurements, Recurring Money market funds	Mar. 31, 2013 Fair Value, Measurements, Recurring Money market funds	Mar. 31, 2014 Fair Value, Measurements, Recurring Other mutual funds	Dec. 31, 2013 Fair Value, Measurements, Recurring Other mutual funds	Mar. 31, 2013 Fair Value, Measurements, Recurring Other mutual funds
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure							$ 3,832,000	$ 2,141,000	$ 1,818,000	$ 118,000	$ 2,014,000	$ 2,000,000	$ 2,023,000
Unrealized gains on the investments			0	0	705,000	700,000
Unrealized gains on the investments after-tax	$ 438,000	$ 429,000