Goodwill - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Forecasted period for income statement and working capital projections to assess goodwill impairment	5 years
Impairment loss as a result of goodwill	$ 0	$ 0	$ 0