PHC Certificates - Additional Information (Details)	3 Months Ended
Mar. 31, 2018 Integer
LIFERS [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Securities, Ownership Percentage	100.00%
Public housing capital fund trusts [Member]
Schedule Of Available For Sale Securities [Line Items]
Number of Available for Sale Securities, Public Housing Authorities	3

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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