Debt (details) (USD $) In Millions, unless otherwise specified	0 Months Ended
May 29, 2012 6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member]	Jun. 15, 2012 5.375% Senior notes due June 15, 2012 [Member]
Debt repayment
Debt, principal amount repaid	$ 8.5	$ 250.0
Interest rate (percent)	6.25%	5.375%

Interest rate stated in the contractual debt agreement.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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