Goodwill and Other Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and intangible asset impairment		$ 0
Amortization of intangible assets	$ 800,000	$ 3,000,000	$ 3,000,000
Future amortization expense, 2018	300,000
Future amortization expense, 2019	300,000
Future amortization expense, 2020	300,000
Future amortization expense, 2021	300,000
Future amortization expense, 2022	$ 300,000