Long-Term Debt - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended
Jan. 31, 2011 Senior Debt Obligations Fixed Rate 3.625 Percent Notes Due 2016	Jun. 30, 2011 Trust Preferred Securities
Debt Disclosure [Line Items]
Issue of senior notes to third party investors	$ 1,000,000,000
Interest rate	3.625%
Maturity date	Jan. 25, 2016
Principal balances of redeemed trust preferred securities, at par, classified as long-term debt		452,000,000
Gain on the extinguishment		$ 6,000,000

Amount represents the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 26
-Paragraph 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629

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Data Type:	xbrli:monetaryItemType
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