Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 83,680	$ 83,680
Other intangible assets	60	420
Accumulated amortization on intangible assets	9,480	9,140
Intangible asset amortization	360	$ 580	$ 690
Expected amortization on other intangible assets
2018	50
2019	$ 10