Segment Information - Total Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 6,938,579	$ 6,934,392
Operating Segments
Segment Reporting Information [Line Items]
Assets	6,766,227	6,737,720
Operating Segments | Other
Segment Reporting Information [Line Items]
Assets	1,152,581	1,153,518
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Assets	172,352	196,672
North America | Operating Segments | Carolinas/Richmond
Segment Reporting Information [Line Items]
Assets	526,631	525,041
North America | Operating Segments | Chicago/Minneapolis
Segment Reporting Information [Line Items]
Assets	588,169	591,792
North America | Operating Segments | Cincinnati/Columbus/Indianapolis
Segment Reporting Information [Line Items]
Assets	132,501	131,400
North America | Operating Segments | Dallas
Segment Reporting Information [Line Items]
Assets	305,929	261,538
North America | Operating Segments | Florida
Segment Reporting Information [Line Items]
Assets	543,304	547,232
North America | Operating Segments | Houston
Segment Reporting Information [Line Items]
Assets	586,409	568,756
North America | Operating Segments | Lehigh/Central PA
Segment Reporting Information [Line Items]
Assets	1,208,754	1,210,220
North America | Operating Segments | Philadelphia
Segment Reporting Information [Line Items]
Assets	609,011	624,373
North America | Operating Segments | Southern California
Segment Reporting Information [Line Items]
Assets	703,117	660,688
United Kingdom | Operating Segments | United Kingdom
Segment Reporting Information [Line Items]
Assets	$ 409,821	$ 463,162