Summary of Significant Accounting Policies Summary of Significant Accounting Policies - Reconciliation of Cash Cash Equivalent and Restricted Cash As Presented in SCF (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 162,600	$ 83,932	$ 87,641	$ 94,808
Restricted Cash, Current	13,137	11,793	12,228	14,609
Restricted cash	17,410	13,646	16,372	36,875
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 193,147	$ 109,371	$ 116,241	$ 146,292