Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands				6 Months Ended	12 Months Ended
	Jul. 19, 2017	Jul. 01, 2017	Apr. 03, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Deposit - Verde consideration				$ 65,785		$ 0
Payments to acquire RCEs			$ 4,900
Anticipated series A preferred stock dividends paid and declared				$ 1,174
Series A Preferred Stock | Scenario, Forecast
Subsequent Event [Line Items]
Anticipated series A preferred stock dividends paid and declared					$ 2,900
Subsequent Event | Common Class A
Subsequent Event [Line Items]
Class A common stock dividends declared (in dollars per share)	$ 0.18125
Subsequent Event | Series A Preferred Stock
Subsequent Event [Line Items]
Series A preferred stock dividend (in dollars per share)	0.546875
Series A preferred stock dividends declared (in dollars per share)	$ 2.1875
Verde Companies | Subsequent Event
Subsequent Event [Line Items]
Purchase price		$ 85,800
Working capital		20,800
Cash used to fund acquisition		6,800
Verde Companies | Subordinated Debt | Subsequent Event
Subsequent Event [Line Items]
Contingent consideration - earnout obligations incurred in connection with acquisitions		15,000
Aggregate principal amount of promissory note		20,000
Deposit - Verde consideration		65,800
Verde Companies | Senior Secured Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Contingent consideration - earnout obligations incurred in connection with acquisitions		$ 44,000