Related Party Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Jun. 30, 2014
Related Party Transaction [Line Items]
Due to Related Parties				$ 300,000
Proceeds from sales of equity investments				4,966	$ 0
Payments to Acquire Equity Method Investments				1,489	$ 1,650
Clause 2 [Member]
Related Party Transaction [Line Items]
Share Price							$ 12.00
Clause 3 [Member]
Related Party Transaction [Line Items]
Share Price							15.00
Management [Member]
Related Party Transaction [Line Items]
Proceeds from sales of equity investments	$ 3,400
Sale of Stock, Number of Shares Issued in Transaction		900,000				475,428
Proceeds from Sale of Treasury Stock						$ 3,700
Share Price		$ 7.85				$ 7.85
Sale of Stock, Consideration Received on Transaction	300
Effect on Future Cash Flows, Amount	$ 1,000
Payments to Acquire Equity Method Investments				$ 1,500
Related Party Transaction, Rate			5.00%
Common Stock [Member] | Management [Member]
Related Party Transaction [Line Items]
Stockholders' Equity, Other Shares		425,000
Effect on Future Cash Flows, Amount						$ 7,100
Corporate Segment [Member]
Related Party Transaction [Line Items]
Effect on Future Cash Flows, Amount			$ 1,300
Investment Owned, Balance, Shares	1,814,000		1,814,000
Sale of Stock, Price Per Share	$ 0.72		$ 0.72
Common Stock [Member] | Management [Member]
Related Party Transaction [Line Items]
Effect on Future Cash Flows, Amount	$ 500
Investment Owned, Balance, Shares	75,000		75,000
Sale of Stock, Price Per Share	$ 7.13		$ 7.13
Minimum [Member]
Related Party Transaction [Line Items]
Share Price							10.00
Maximum [Member]
Related Party Transaction [Line Items]
Share Price							$ 18.00