Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Liabilities:
Derivative liabilities	$ 1,283	$ 2,879
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	155,904	169,656
Restricted cash and cash equivalents	98,137	98,884
Total	254,041	268,540
Liabilities:
Derivative liabilities	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Total	0	0
Liabilities:
Derivative liabilities	1,283	2,879
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Total	0	0
Liabilities:
Derivative liabilities	0	0
Estimate of Fair Value Measurement | Recurring
Assets:
Cash and cash equivalents	155,904	169,656
Restricted cash and cash equivalents	98,137	98,884
Total	254,041	268,540
Liabilities:
Derivative liabilities	$ 1,283	$ 2,879