Equity Compensation Equity compensation expense by grant (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.175	$ 0.2625	$ 0.6125	$ 0.785
Share-based Compensation	$ (152,000)	$ 0	$ 5,463,000	$ 0
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	5,985,000		5,985,000
Employee Benefits and Share-based Compensation	582,000	305,000	1,058,000	$ 922,000
ClassBUnits [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Dividends, Per Share, Declared				$ 0.25
Share-based Compensation					$ 65,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation			548,000
2016 [Member] | ClassBUnits [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	0		0
Employee Benefits and Share-based Compensation	0	0	0	$ 2,000
2017 | ClassBUnits [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	0		0
Employee Benefits and Share-based Compensation	0	78,000	3,000	234,000
2017 | Restricted Stock Units outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	0		0
Employee Benefits and Share-based Compensation	0	15,000	0	53,000
2014 [Member] | ClassBUnits [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	71,000		71,000
2014 [Member] | 2011restrictedstockgrant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	0		0
Employee Benefits and Share-based Compensation	0	0	0	120,000
2014 [Member] | Restricted Stock Units outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	19,000		19,000
Employee Benefits and Share-based Compensation	14,000	15,000	38,000	55,000
2019 | 2011restrictedstockgrant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	0		0
Employee Benefits and Share-based Compensation	0	106,000	140,000	176,000
2019 | Restricted Stock Units outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	94,000		94,000
Employee Benefits and Share-based Compensation	16,000	19,000	47,000	67,000
2018 | ClassBUnits [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Benefits and Share-based Compensation	70,000	72,000	191,000	215,000
2020 | Performance based restricted stock units | Share-based Payment Arrangement, Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	1,753,000		1,753,000
Employee Benefits and Share-based Compensation	92,000	0	92,000	0
2020 | 2011restrictedstockgrant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	310,000		310,000
Employee Benefits and Share-based Compensation	133,000	0	222,000	0
2020 | 2011restrictedstockgrant | Share-based Payment Arrangement, Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	3,601,000		3,601,000
Employee Benefits and Share-based Compensation	242,000	0	279,000	0
2020 | Restricted Stock Units outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	137,000		137,000
Employee Benefits and Share-based Compensation	$ 15,000	$ 0	$ 46,000	$ 0