Investment in Limited Partnerships (Parenthetical) (Detail)	Dec. 31, 2012	Dec. 31, 2011
Pedcor Investments 1997-XXVIII
Schedule of Equity Method Investments [Line Items]
Ownership, percentage	99.00%	99.00%
Pedcor Investments 1987-XXXI
Schedule of Equity Method Investments [Line Items]
Ownership, percentage	49.50%	49.50%
Pedcor Investments 2000-XLI
Schedule of Equity Method Investments [Line Items]
Ownership, percentage	50.00%	50.00%
Pedcor Investments 2001-LI
Schedule of Equity Method Investments [Line Items]
Ownership, percentage	9.90%	9.90%
Pedcor Investments 2008-CIII
Schedule of Equity Method Investments [Line Items]
Ownership, percentage	21.50%	21.50%

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant