Segment Information - Total Assets by Segment (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Assets	$ 6,731,739,000	$ 6,775,560,000
Operating Segments [Member]
Segment Reporting Information [Line Items]
Assets	6,463,249,000	6,542,540,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	268,490,000	233,020,000
North America [Member] | Operating Segments [Member] | Carolinas [Member]
Segment Reporting Information [Line Items]
Assets	303,215,000	257,230,000
North America [Member] | Operating Segments [Member] | Chicago Milwaukee [Member]
Segment Reporting Information [Line Items]
Assets	416,197,000	413,585,000
North America [Member] | Operating Segments [Member] | Houston [Member]
Segment Reporting Information [Line Items]
Assets	401,045,000	380,248,000
North America [Member] | Operating Segments [Member] | Lehigh Central PA [Member]
Segment Reporting Information [Line Items]
Assets	972,962,000	938,824,000
North America [Member] | Operating Segments [Member] | Minnesota [Member]
Segment Reporting Information [Line Items]
Assets	343,894,000	335,613,000
North America [Member] | Operating Segments [Member] | Orlando [Member]
Segment Reporting Information [Line Items]
Assets	255,915,000	253,888,000
North America [Member] | Operating Segments [Member] | Philadelphia [Member]
Segment Reporting Information [Line Items]
Assets	336,783,000	316,810,000
North America [Member] | Operating Segments [Member] | Richmond Hampton Roads [Member]
Segment Reporting Information [Line Items]
Assets	248,446,000	250,008,000
North America [Member] | Operating Segments [Member] | South Florida [Member]
Segment Reporting Information [Line Items]
Assets	379,976,000	380,138,000
North America [Member] | Operating Segments [Member] | Southeastern PA [Member]
Segment Reporting Information [Line Items]
Assets	699,676,000	695,966,000
North America [Member] | Operating Segments [Member] | Tampa [Member]
Segment Reporting Information [Line Items]
Assets	336,012,000	337,300,000
North America [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	1,504,110,000	1,735,393,000
European Union [Member] | Operating Segments [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Assets	$ 265,018,000	$ 247,537,000