Senior Debt Senior Debt (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Senior Debt [Abstract]
Required minimum consolidated fixed charge coverage ratio	1.10
Actual consolidated fixed charge coverage ratio	3.64
Adjusted consolidated ebitda	$ 156,400
Consolidated fixed charges	42,900
Debt Instrument [Line Items]
Unamortized debt issuance expense	2,600	$ 5,173
Senior debt, net	0	134,125
Letters of credit, amount outstanding	$ 92,000	94,000
Commitment fee percentage	0.50%
Commitment fee amount	$ 1,000
Senior credit facilities, additional amount allowed	100,000
Write-off of debt issuance costs	475	1,936	$ 0
Debt arrangement and amendment fees	$ 2,100
Event of default - 3rd party ownership % of our voting stock	35.00%
Event of default-not satisfied or bonded judgment in excess of	$ 50,000
Maximum period allowed for pending judgment to satisfy	30
Minimum [Member]
Debt Instrument [Line Items]
Commitment fee percentage	0.30%
Maximum [Member]
Debt Instrument [Line Items]
Commitment fee percentage	0.50%
Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 0	225,000
Term Loan Amount Outstanding	0	48,563
Amount available	0	0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	200,000	350,000
Long-term Line of Credit	$ 0	85,000
Maturity date	Dec. 31, 2019
Revolving credit facility availability	$ 95,900	109,700
Revolving Credit Facility [Member] | Eurodollar [Member]
Debt Instrument [Line Items]
Margin on Eurodollar rate	2.00%
Revolving Credit Facility [Member] | Eurodollar [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	1.50%
Revolving Credit Facility [Member] | Eurodollar [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	3.00%
Revolving Credit Facility [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Margin on prime rate	1.00%
Revolving Credit Facility [Member] | Prime Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	0.50%
Revolving Credit Facility [Member] | Prime Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	2.00%
Term Loan and Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 200,000	575,000
Amount outstanding	0	133,563
Amount available	$ 95,900	109,700
Line of Credit [Member]
Debt Instrument [Line Items]
Maturity date	Aug. 20, 2019
Unsecured line of credit, maximum facility	$ 12,500	12,500
Unsecured line of credit, amount outstanding	0	5,735
Amount available	12,500	6,765
Senior Debt [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	212,500	587,500
Amount outstanding	0	139,298
Amount available	108,400	$ 116,465
Dividend annual limit [Member]
Debt Instrument [Line Items]
Equity restrictions	$ 15,000