Segment Operating Results - Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total Assets	$ 2,725,913	$ 3,370,888	$ 2,221,552
United States [Member]
Segment Reporting Information [Line Items]
Total Assets	2,245,175	2,862,343
Europe And Other [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 480,738	$ 508,545