Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Mar. 13, 2017	Sep. 01, 2016
Line of Credit Facility [Line Items]
Interest Expense, Debt	$ 242
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.65%
Revolving Credit Facility [Member] | Wells Fargo Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 100,000
Line of Credit Facility, Fair Value of Amount Outstanding	$ 64,500
Debt Instrument, Maturity Date	Sep. 01, 2019
Debt Instrument, Covenant, Minimum EBITDA	$ 75,000
Letters of Credit Outstanding, Amount	$ 16,700
Debt Instrument, Covenant Description	The only financial covenant in the credit facility requires the Company's minimum EBITDA to be at least $75.0 million.
Revolving Credit Facility [Member] | Wells Fargo Bank, N.A. [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 120,000
Line of Credit [Member] | Wells Fargo Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 50,000