Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair value information related to assets
Assets	$ 11,416	$ 22,235
Other mutual funds [Member]
Fair value information related to assets
Assets	1,239	1,373
Money market funds [Member]
Fair value information related to assets
Assets	10,177	20,862
Quoted Prices in Active Markets (Level 1) [Member]
Fair value information related to assets
Assets	11,416	22,235
Quoted Prices in Active Markets (Level 1) [Member] | Other mutual funds [Member]
Fair value information related to assets
Assets	1,239	1,373
Quoted Prices in Active Markets (Level 1) [Member] | Money market funds [Member]
Fair value information related to assets
Assets	10,177	20,862
Significant Other Observable Inputs (Level 2) [Member]
Fair value information related to assets
Assets
Significant Other Observable Inputs (Level 2) [Member] | Other mutual funds [Member]
Fair value information related to assets
Assets
Significant Other Observable Inputs (Level 2) [Member] | Money market funds [Member]
Fair value information related to assets
Assets
Significant Unobserved Inputs (Level 3) [Member]
Fair value information related to assets
Assets
Significant Unobserved Inputs (Level 3) [Member] | Other mutual funds [Member]
Fair value information related to assets
Assets
Significant Unobserved Inputs (Level 3) [Member] | Money market funds [Member]
Fair value information related to assets
Assets