Goodwill and Intangible Assets - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) acquisition	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) acquisition	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Number of acquisitions resulting in goodwill | acquisition	4		4
Goodwill					$ 6,600,000
Goodwill impairment loss			$ 0		$ 0
Intangible asset amortization	$ 58,000	$ 60,000	$ 177,000	$ 165,000