Issuance of Common Stock (Details) - USD ($) $ in Thousands		3 Months Ended
	Mar. 28, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Equity [Abstract]
Common stock shares issued (in shares)	5,175,000	50,346,000		50,248,000
Proceeds from issuance of common stock	$ 136,600	$ 1,511	$ 138,569
Underwriting discounts and commissions	8,800
Other direct costs incurred	$ 816	$ 0	$ 833