Common Stock And Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands			12 Months Ended
	Jul. 30, 2018	Mar. 28, 2017	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Shares of common stock sold in public offering (in shares)	4,025,000	5,175,000
Procceds from public offering, net	$ 205,000	$ 136,600
Underwriting discounts and commissions	12,000	8,800
Other direct costs incurred	$ 366	$ 816	$ 366	$ 816