Fair Value of Financial Instruments Narrative Tagging (Details)	Sep. 30, 2017	Dec. 31, 2016
Effective rate - minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Effective rate	2.60%	4.90%
Effective rate - minimum [Member] | Public housing capital fund trusts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Effective rate		4.30%
Effective rate - maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Effective rate	9.90%	12.40%
Effective rate - maximum [Member] | Public housing capital fund trusts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Effective rate		6.00%