Long Term Debt (Narrative) (Details) - USD ($)		3 Months Ended	12 Months Ended
	Jan. 04, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Loss on early extinguishment of debt		$ 300,000	$ 254,000	$ 0	$ 0
Long-term debt outstanding			$ 498,490,000	270,810,000
Interest rate at period end (percent)			2.77%
Debt Instrument, Financing Costs Expensed		$ 2,700,000	$ 2,700,000
Amended and Restated Senior Credit Agreement [Member] | Eurodollar [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	2.00%
Amended and Restated Senior Credit Agreement [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.00%
Revolving Line of Credit [Member]
Debt Instrument [Line Items]
Long-term debt outstanding			329,000,000	265,609,000
Line of credit facility, available borrowing capacity			191,200,000
Revolving Line of Credit [Member] | Amended and Restated Senior Credit Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 525,000,000.0
Letters of Credit [Member]
Debt Instrument [Line Items]
Letters of credit outstanding			4,800,000
Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			166,300,000
Long-term debt outstanding			165,628,000	0
Term Loan Facility [Member] | Amended and Restated Senior Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 175,000,000.0
Mortgages Notes [Member]
Debt Instrument [Line Items]
Long-term debt outstanding			$ 3,862,000	$ 5,201,000
Debt interest rate (percent)			8.25%