Segment Information Total Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Assets	$ 6,722,922	$ 6,557,629
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	6,651,464	6,493,176
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	71,458	64,453
North America [Member] | Operating Segments [Member] | Carolinas Richmond [Member]
Segment Reporting Information [Line Items]
Assets	493,798	467,098
North America [Member] | Operating Segments [Member] | Chicago Milwaukee [Member]
Segment Reporting Information [Line Items]
Assets	433,679	429,390
North America [Member] | Operating Segments [Member] | Florida [Member]
Segment Reporting Information [Line Items]
Assets	796,806	874,352
North America [Member] | Operating Segments [Member] | Houston [Member]
Segment Reporting Information [Line Items]
Assets	530,388	522,285
North America [Member] | Operating Segments [Member] | Lehigh Central PA [Member]
Segment Reporting Information [Line Items]
Assets	1,293,980	1,157,468
North America [Member] | Operating Segments [Member] | Minnesota [Member]
Segment Reporting Information [Line Items]
Assets	346,797	346,840
North America [Member] | Operating Segments [Member] | Philadelphia [Member]
Segment Reporting Information [Line Items]
Assets	517,956	444,889
North America [Member] | Operating Segments [Member] | Southeastern PA [Member]
Segment Reporting Information [Line Items]
Assets	449,288	448,523
North America [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	1,601,797	1,586,481
UNITED KINGDOM | Operating Segments [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Assets	$ 186,975	$ 215,850