Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Cash and Cash Equivalents [Line Items]
Unrealized gains on the investments after-tax	$ 408	$ 346
Money market funds
Cash and Cash Equivalents [Line Items]
Realized gains on the investments	0
Unrealized gains on the investments	0
Other mutual funds
Cash and Cash Equivalents [Line Items]
Unrealized gains on the investments	700	600
Unrealized gains on the investments after-tax	400	300
Fair Value, Measurements, Recurring
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	2,170	2,310
Fair Value, Measurements, Recurring | Money market funds
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	118	118
Fair Value, Measurements, Recurring | Other mutual funds
Cash and Cash Equivalents [Line Items]
Assets, Fair Value Disclosure	$ 2,052	$ 2,192