Fair Value Measurements - Investments in Company-Sponsored Funds (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Investment Holdings [Line Items]
Fair Value	$ 8,827,000
Unfunded Commitments	1,251,000
Hedge Funds
Investment Holdings [Line Items]
Fair Value	2,159,000	[1]
Unfunded Commitments	0	[1]
Redemption Frequency	Quarterly - Annually	[1]
Redemption Notice Period, Minimum	30 days	[1]
Redemption Notice Period, Maximum	120 days	[1]
Private Equity Funds
Investment Holdings [Line Items]
Fair Value	6,668,000	[2]
Unfunded Commitments	1,251,000	[2]
Auction rate securities
Investment Holdings [Line Items]
Assets and liabilities transferred from level one and level two	$ 0		$ 0

[1] Includes investments in hedge funds and hedge fund of funds that pursue long/short, event-driven, and activist strategies. Each hedge fund has various restrictions regarding redemption; no investment is locked-up for a period greater than one year.

[2] Includes private equity funds and private equity fund of funds with a focus on diversified portfolios, real estate and global natural resources. Due to the illiquid nature of these funds, investors are not permitted to make withdrawals without consent of the general partner. The lock-up period of the private equity funds can extend to 10 years.