Fair Value Measurements - Recurring and Nonrecurring Basis (Details) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Fair value information related to assets
Assets	$ 3,832		$ 2,141
Money market funds
Fair value information related to assets
Assets	1,818		118
Other mutual funds
Fair value information related to assets
Assets	2,014	2,000	2,023
Quoted Prices in Active Markets (Level 1)
Fair value information related to assets
Assets	3,832		2,141
Quoted Prices in Active Markets (Level 1) | Money market funds
Fair value information related to assets
Assets	1,818		118
Quoted Prices in Active Markets (Level 1) | Other mutual funds
Fair value information related to assets
Assets	2,014		2,023
Significant Other Observable Inputs (Level 2)
Fair value information related to assets
Assets	0		0
Significant Other Observable Inputs (Level 2) | Money market funds
Fair value information related to assets
Assets	0		0
Significant Other Observable Inputs (Level 2) | Other mutual funds
Fair value information related to assets
Assets	0		0
Significant Unobserved Inputs (Level 3)
Fair value information related to assets
Assets	0		0
Significant Unobserved Inputs (Level 3) | Money market funds
Fair value information related to assets
Assets	0		0
Significant Unobserved Inputs (Level 3) | Other mutual funds
Fair value information related to assets
Assets	$ 0		$ 0