Segment Information - Total Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Document Period End Date	Jun. 30, 2019
Assets	$ 6,882,259	$ 6,934,394
Operating Segments
Segment Reporting Information [Line Items]
Assets	6,814,334	6,737,720
Operating Segments | Other
Segment Reporting Information [Line Items]
Assets	1,165,094	1,153,518
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Assets	67,925	196,674
North America | Operating Segments | Carolinas/Richmond
Segment Reporting Information [Line Items]
Assets	524,408	525,041
North America | Operating Segments | Chicago/Minneapolis
Segment Reporting Information [Line Items]
Assets	584,471	591,792
North America | Operating Segments | Cincinnati/Columbus/Indianapolis
Segment Reporting Information [Line Items]
Assets	133,848	131,400
North America | Operating Segments | Dallas
Segment Reporting Information [Line Items]
Assets	305,282	261,538
North America | Operating Segments | Florida
Segment Reporting Information [Line Items]
Assets	546,815	547,232
North America | Operating Segments | Houston
Segment Reporting Information [Line Items]
Assets	605,443	568,756
North America | Operating Segments | Lehigh/Central PA
Segment Reporting Information [Line Items]
Assets	1,205,634	1,210,220
North America | Operating Segments | Philadelphia
Segment Reporting Information [Line Items]
Assets	624,370	624,373
North America | Operating Segments | Southern California
Segment Reporting Information [Line Items]
Assets	713,262	660,688
United Kingdom | Operating Segments | United Kingdom
Segment Reporting Information [Line Items]
Assets	$ 405,707	$ 463,162