Segment Operating Results - Assets by Geographic Area (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Segment Reporting Information [Line Items]
Assets	$ 1,561,035	$ 1,662,346	$ 1,461,630
United States [Member]
Segment Reporting Information [Line Items]
Assets	1,280,698	1,376,101
Europe and Other [Member]
Segment Reporting Information [Line Items]
Assets	207,605	190,380
Latin America [Member]
Segment Reporting Information [Line Items]
Assets	$ 72,732	$ 95,865