Business Segments (Details 1) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total assets	$ 6,293,847	$ 6,118,681
Operating Segments [Member] | Conventional Real Estate [Member]
Segment Reporting Information [Line Items]
Total assets	5,365,047	4,979,504
Operating Segments [Member] | Affordable Real Estate [Member]
Segment Reporting Information [Line Items]
Total assets	394,086	409,165
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Total assets	172,111	174,202
Corporate Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 362,603	$ 555,810