Segment Operating Results - Assets by Geographic Area (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Segment Reporting Information [Line Items]
Total Assets	$ 2,947,448	$ 3,370,888	$ 2,499,589
United States [Member]
Segment Reporting Information [Line Items]
Total Assets	2,433,168	2,862,343
Europe And Other [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 514,280	$ 508,545