Fair Value Measurements - Summary of Fair Value Assets Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Fair value information related to assets
Assets		$ 2,756	$ 2,180
Quoted Prices in Active Markets (Level 1)
Fair value information related to assets
Assets		2,756	2,180
Money market funds
Fair value information related to assets
Assets	[1]	119	118
Money market funds | Quoted Prices in Active Markets (Level 1)
Fair value information related to assets
Assets	[1]	119	118
Other mutual funds
Fair value information related to assets
Assets	[2]	2,637	2,062
Other mutual funds | Quoted Prices in Active Markets (Level 1)
Fair value information related to assets
Assets	[2]	$ 2,637	$ 2,062

[1] Money market funds are included in “Cash and cash equivalents” in the Consolidated Balance Sheets. These investments are classified as available-for-sale and are recorded at fair value. There have been no realized gains or losses related to these investments and we have not experienced any redemption restrictions with respect to any of the money market mutual funds.

[2] Other mutual funds are included in “Other investments and assets” in the Consolidated Balance Sheets. These investments are classified as available-for-sale and are recorded at fair value. Unrealized gains of $1.0 million ($0.6 million after-tax) as of December 31, 2017 and $0.7 million ($0.4 million after tax) as of December 31, 2016 are included in “Accumulated other comprehensive income (loss)” (“AOCI”) in the Consolidated Balance Sheets.