Long-Term Debt (Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Coupon interest at 3.75%	$ 12,188	$ 12,188	$ 11,240
Amortization of debt issuance costs	1,424	1,424	1,305
Total interest expense on the Notes	$ 13,612	$ 13,612	$ 12,545