Summarized Quarterly Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income Statements, Captions [Line Items]
Total revenues	$ 151,428	$ 144,936	$ 139,245	$ 146,189	$ 155,568	$ 116,465	$ 117,542	$ 116,848	$ 581,798	$ 506,423	$ 392,331
Total expenses	151,060	151,414	147,045	146,066	149,691	108,474	110,253	109,119	595,585	477,537	388,346
Other Income	1,064	2,583	2,895	3,915	10,205	4,032	4,912	1,105	10,457	20,254	(6,889)
Net income (loss) before taxes from continuing operations	1,432	(3,895)	(4,905)	4,038	16,082	12,023	12,201	8,834	(3,330)	49,140	(2,904)
Less: provision (benefit) for income taxes	(11,284)	(1,541)	(1,305)	1,568	6,363	3,532	3,921	(1,301)	(12,562)	12,515	(753)
Net income (loss) from continuing operations	12,716	(2,354)	(3,600)	2,470	9,719	8,491	8,280	10,135	9,232	36,625	(2,151)
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax	(863)	(1,535)	(2,294)	(1,530)	(337)	(473)	(1,155)	(3,859)	(6,222)	(5,824)	1,260
Less: Provision (benefit) for income taxes	(741)	(511)	(570)	(402)	(683)	180	104	(1,138)	(2,224)	(1,537)	17,527
Discontinued operations, net	(122)	(1,024)	(1,724)	(1,128)	346	(653)	(1,259)	(2,721)	(3,998)	(4,287)	10,953
Net income (loss) before non-controlling interests	12,594	(3,378)	(5,324)	1,342	10,065	7,838	7,021	7,414	5,234	32,338	8,802
Less: net (loss) income attributable to non-controlling interests	2,533	(264)	(881)	242	2,338	1,933	888	1,859
Net income (loss) available to common stockholders	$ 10,061	$ (3,114)	$ (4,443)	$ 1,100	$ 7,727	$ 5,905	$ 6,133	$ 5,555	$ 3,604	$ 25,320	$ 5,779
Common Stock - Class A
Basic:
Basic, net	$ 0.34	$ (0.08)	$ (0.11)	$ 0.07	$ 0.26	$ 0.22	$ 0.20	$ 0.21	$ 0.22	$ 0.88	$ (0.01)
Basic, discontinued operations, net	(0.01)	(0.03)	(0.04)	(0.03)	0.01	(0.02)	(0.02)	(0.05)	(0.10)	(0.09)	0.18
Basic earnings per share	0.33	(0.11)	(0.15)	0.04	0.27	0.20	0.18	0.16	0.12	0.79	0.17
Diluted:
Diluted, net	0.32	(0.08)	(0.11)	0.06	0.24	0.21	0.20	0.20	0.21	0.86	(0.01)
Diluted, discontinued operations, net	(0.01)	(0.03)	(0.04)	(0.03)	0.01	(0.02)	(0.03)	(0.04)	(0.10)	(0.08)	0.18
Diluted earnings per share	$ 0.31	$ (0.11)	$ (0.15)	$ 0.03	$ 0.25	$ 0.19	$ 0.17	$ 0.16	$ 0.11	$ 0.78	$ 0.17
Weighted average number of Class A common shares:
Basic	29,804,802	29,455,462	28,832,975	28,424,824	28,374,850	29,143,470	34,456,096	34,976,485	29,134,190	31,721,449	33,202,681
Diluted	37,853,831	29,455,462	28,832,975	36,749,956	36,630,783	37,230,650	34,528,977	35,084,505	37,306,632	31,766,674	33,202,681