Income Tax Expense (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, Beginning balance	$ 8,928	$ 7,808
Additions for tax positions related to prior periods	1,654	50
Decreases related to prior year tax positions	(95)	0
Lapse of statute of limitations	0	0
Additions for tax positions related to current period	1,267	1,070
Unrecognized tax benefits, Ending balance	$ 11,754	$ 8,928