Stockholders' Equity (Details) - Common Stock - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Class of Stock [Line Items]
Aggregate offering price		$ 75,000,000.0
Commission rate (percent)		3.00%
Stock issued (in shares)	740,417
Proceeds from stock issuance	$ 30,300,000
Underwriting discounts and commissions and other offering expenses	$ 1,100,000