Description of Business and Summary of Significant Accounting Policies Cash, Cash Equivalents, and Restricted Cash Shown in the Statement of Cash Flows (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 124,242	$ 147,766	$ 134,987
Restricted Cash and Cash Equivalents, Current	18,240	8,317	0
Restricted Cash, Noncurrent	6,568		2,523
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 149,050	$ 159,589	$ 137,510	$ 70,867