Fair Value Measurements (Detail 3) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Minimum
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Adjustments to appraised values from use of comparable sales values or income approaches (as a percent)	12.00%
Adjustments to investment carrying amounts (as a percent)	27.00%
Maximum
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Adjustments to appraised values from use of comparable sales values or income approaches (as a percent)	22.00%
Adjustments to investment carrying amounts (as a percent)	86.00%
Other real estate owned
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Fair value of assets	$ 9,544
Private equity and alternative investments
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Fair value of assets	1,587
Fair Value \| Measured on a Recurring Basis
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Fair value of assets	5,548,674	$ 6,110,687
Fair Value \| Measured on a Nonrecurring Basis
Information about valuation method, inputs and assumptions for nonrecurring Level 3 fair value measurements
Fair value of assets	$ 11,131	$ 5,644

Percentage of adjustment to the carrying amounts of investments accounted for under the cost method of accounting.

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

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.

+ References

No definition available.

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- Definition

Percentage of adjustment to the observed price for a similar asset or liability when an identical transaction does not exist, used as an input to measure fair value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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