Debt Transactions (Details) - USD ($)	Apr. 05, 2016	Mar. 31, 2016
Senior Notes [Member] \| Senior Notes due June 15, 2016 [Member]
Debt Instrument [Line Items]
Principal amount		$ 250,000,000
Stated interest rate		6.375%
Subsequent Event [Member] \| Junior Subordinated Debt [Member] \| Junior Subordinated Debentures due 2056 [Member]
Debt Instrument [Line Items]
Principal amount	$ 300,000,000
Stated interest rate	6.125%
Proceeds from sale of debentures net of underwriting discount and offering expenses	$ 290,000,000

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: 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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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

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- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

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