Summary of Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash deposits
Cash deposits with U.S. financial institutions in excess of federally insured limits	$ 4,800	$ 0
Cash and cash equivalents	37,984	53,629	$ 53,133	$ 32,942
Foreign subsidiaries
Cash deposits
Cash and cash equivalents	$ 27,400	$ 45,100