Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017
Goodwill Disclosure [Abstract]
Accumulated impairment losses of goodwill		$ 0
Goodwill [Roll Forward]
Balance at beginning of period	$ 8,928
Return of purchase price from escrow	(125)
Balance at end of period	$ 8,803