Investments in Unconsolidated Joint Ventures Investments in Unconsolidated Joint Ventures - Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule of Equity Method Investments [Line Items]
Total operating revenue	$ 264,425	$ 197,168
Cost of sales	(251,145)	(187,021)
Operating income (loss)	13,280	10,147
Unconsolidated joint venture income	1,181	248
Joint Ventures
Schedule of Equity Method Investments [Line Items]
Total operating revenue	3,967	706
Cost of sales	(1,925)	(382)
Operating income (loss)	$ 2,042	$ 324