Senior Debt (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Senior Debt (Table Details) [Abstract]
Senior credit facility, maximum amount	$ 350,000,000		$ 350,000,000		$ 350,000,000
Term loan, amount outstanding	49,700,000		49,700,000		49,700,000	$ 191,800,000
Revolving facility, amount outstanding	55,000,000		55,000,000		55,000,000	0
Unamortized Debt Issuance Expense	7,100,000		7,100,000		7,100,000	5,100,000
Mandatory Excess Cash Flow Pre-Payment			141,000,000			$ 27,000,000
Debt refinancing charges	1,936,000	$ 0	1,936,000	$ 0
Debt arrangement and amendment fees			5,100,000
Letters of credit, amount outstanding	91,100,000		$ 91,100,000		91,100,000
Commitment fee percentage			0.50%
Senior credit facilities, additional amount allowed	$ 100,000,000		$ 100,000,000		$ 100,000,000
Financial Covenants Ratios (Table Details) [Abstract]
Required consolidated fixed charge coverage ratio, minimum	1.1		1.1		1.1
Actual consolidated fixed charge coverage ratio	0.77		0.77		0.77
Covenants [Abstract]
Covenants for senior credit facilities - amount available under restricted payment basket	$ 15,000,000		$ 15,000,000		$ 15,000,000
Adjusted consolidated EBITDA					36,800,000
Consolidated fixed charges					$ 48,000,000
Event of default-3rd party ownership % of our voting stock	35.00%		35.00%		35.00%
Event of default-not satisfied or bonded judgment in excess of	$ 50,000,000		$ 50,000,000		$ 50,000,000
Maximum period allowed for pending judgment to satisfy or bond (in days)	30		30		30
Unsecured line of credit, maximum facility	$ 20,000,000		$ 20,000,000		$ 20,000,000
Unsecured line of credit, amount outstanding	0		0		0
Maturities of Long-term Debt [Abstract]
2017	1,125,000		1,125,000		1,125,000
2018	2,250,000		2,250,000		2,250,000
2019	57,250,000		57,250,000		57,250,000
2020	2,250,000		2,250,000		2,250,000
2021	41,813,000		41,813,000		41,813,000
Thereafter	0		0		0
Total senior debt	104,688,000		104,688,000		104,688,000
Dividend annual limit [Member]
Senior Debt (Table Details) [Abstract]
Equity Restrictions	15,000,000		15,000,000		15,000,000
Dividend paid [Member]
Senior Debt (Table Details) [Abstract]
Equity Restrictions	8,500,000		8,500,000		8,500,000
Dividend declared [Member]
Senior Debt (Table Details) [Abstract]
Equity Restrictions	4,300,000		$ 4,300,000		4,300,000
Minimum [Member]
Senior Debt (Table Details) [Abstract]
Commitment fee percentage			0.30%
Maximum [Member]
Senior Debt (Table Details) [Abstract]
Commitment fee percentage			0.50%
Prime Rate [Member]
Senior Debt (Table Details) [Abstract]
Description of variable rate basis			prime
Eurodollar [Member]
Senior Debt (Table Details) [Abstract]
Description of variable rate basis			Eurodollar rate
Line of Credit [Member]
Senior Debt (Table Details) [Abstract]
Maturity date			Aug. 21, 2017
Covenants [Abstract]
Unsecured line of credit, amount outstanding	0		$ 0		0
Maturities of Long-term Debt [Abstract]
2017	0		0		0
2018	0		0		0
2019	0		0		0
2020	0		0		0
2021	0		0		0
Thereafter	0		0		0
Revolving Credit Facility [Member]
Senior Debt (Table Details) [Abstract]
Revolving facility, amount outstanding	55,000,000		$ 55,000,000		55,000,000
Maturity date			Mar. 19, 2019
Covenants [Abstract]
Line of Credit Facility, Remaining Borrowing Capacity	143,400,000		$ 143,400,000		143,400,000
Maturities of Long-term Debt [Abstract]
2017	0		0		0
2018	0		0		0
2019	55,000,000		55,000,000		55,000,000
2020	0		0		0
2021	0		0		0
Thereafter	$ 0		$ 0		$ 0
Revolving Credit Facility [Member] | Prime Rate [Member]
Senior Debt (Table Details) [Abstract]
Margin on Prime Rate, actual	2.00%		2.00%		2.00%
Revolving Credit Facility [Member] | Prime Rate [Member] | Minimum [Member]
Senior Debt (Table Details) [Abstract]
Basis margin on variable rate			0.50%
Revolving Credit Facility [Member] | Prime Rate [Member] | Maximum [Member]
Senior Debt (Table Details) [Abstract]
Basis margin on variable rate			2.00%
Revolving Credit Facility [Member] | Eurodollar [Member]
Senior Debt (Table Details) [Abstract]
Margin on Eurodollar rate, actual	3.00%		3.00%		3.00%
Revolving Credit Facility [Member] | Eurodollar [Member] | Minimum [Member]
Senior Debt (Table Details) [Abstract]
Basis margin on variable rate			1.50%
Revolving Credit Facility [Member] | Eurodollar [Member] | Maximum [Member]
Senior Debt (Table Details) [Abstract]
Basis margin on variable rate			3.00%
Term Loan [Member]
Senior Debt (Table Details) [Abstract]
Term loan, amount outstanding	$ 49,688,000		$ 49,688,000		$ 49,688,000
Maturity date			Mar. 19, 2021
Term Loan, Periodic Payment, Principal			$ 562,500
Margin on Eurodollar rate, actual	3.00%		3.00%		3.00%
Margin on Prime Rate, actual	2.00%		2.00%		2.00%
Maturities of Long-term Debt [Abstract]
2017	$ 1,125,000		$ 1,125,000		$ 1,125,000
2018	2,250,000		2,250,000		2,250,000
2019	2,250,000		2,250,000		2,250,000
2020	2,250,000		2,250,000		2,250,000
2021	41,813,000		41,813,000		41,813,000
Thereafter	$ 0		$ 0		$ 0