Issuance of Common Stock (Details) - USD ($)		3 Months Ended
	Mar. 28, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Equity [Abstract]
Common stock shares issued (in shares)	5,175,000	49,891,000		44,645,000
Proceeds from issuance of common stock	$ 136,500,000	$ 138,569,000	$ 557,000
Underwriting discounts and commissions	8,800,000
Other direct costs incurred	$ 833,000	$ 833,000	$ 0