Equity Method Investments - The Company's Investment in Joint Ventures (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 16,856	$ 18,563
ICP [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	16,472	18,179
DMI [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 384	$ 384