Stockholders' Equity - Reconciliation of Common Stock (Details) - shares	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in shares)	18,085,798	12,988,482
Issuance of common stock (in shares)	234,000	4,887,500
Restricted stock-based awards (in shares)	214,004	209,816
Balance, end of period (in shares)	18,533,802	18,085,798