Segment Information - Total Assets by Segment (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Assets	$ 6,625,536,000	$ 6,775,560,000
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	6,519,578,000	6,542,540,000
Operating Segments [Member] | Carolinas [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	325,690,000	257,230,000
Operating Segments [Member] | Chicago Milwaukee [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	422,531,000	413,585,000
Operating Segments [Member] | Houston [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	418,154,000	380,248,000
Operating Segments [Member] | Lehigh Central PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	1,023,641,000	938,824,000
Operating Segments [Member] | Minnesota [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	333,506,000	335,613,000
Operating Segments [Member] | Orlando [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	160,899,000	253,888,000
Operating Segments [Member] | Philadelphia [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	366,577,000	316,810,000
Operating Segments [Member] | Richmond Hampton Roads [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	250,205,000	250,008,000
Operating Segments [Member] | South Florida [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	400,034,000	380,138,000
Operating Segments [Member] | Southeastern PA [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	698,163,000	695,966,000
Operating Segments [Member] | Tampa [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	335,652,000	337,301,000
Operating Segments [Member] | United Kingdom [Member] | UNITED KINGDOM
Segment Reporting Information [Line Items]
Assets	231,276,000	247,537,000
Operating Segments [Member] | Other Segments [Member] | North America [Member]
Segment Reporting Information [Line Items]
Assets	1,553,250,000	1,735,392,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	$ 105,958,000	$ 233,020,000