Increase in percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Debt Instrument, Incremental Decrease in Basis Spread on Variable Rate Resulting from Upgrades

+ References

No definition available.

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- Definition

Debt Instrument, Incremental Increase in Basis Spread on Variable Rate Resulting from Downgrades

+ References

No definition available.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM format.

+ References

No definition available.

+ Details

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- Definition

Debt Instrument, Percentage of Face Amount, Sold to Public

+ References

No definition available.

+ Details

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- Definition

Purchase Of Note Principal

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- 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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- 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

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: 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=49170532&loc=d3e12317-112629

Reference 2: 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=98514028&loc=d3e3602-108585

Reference 3: 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=49170532&loc=d3e12355-112629

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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

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

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Balance Type:	credit
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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Debt (Senior Notes - Narrative) (Details) - USD ($) $ in Millions	1 Months Ended				3 Months Ended	6 Months Ended	12 Months Ended
	May 31, 2017	Mar. 31, 2017	Jul. 31, 2016	Jan. 31, 2015	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Net loss on extinguishment of debt					$ (10.0)	$ (11.0)
Unamortized debt expense					24.0	24.0	$ 28.0
Long-term Debt [Member]
Debt Instrument [Line Items]
Net loss on extinguishment of debt	$ (10.0)
Unamortized debt expense					$ 24.0	$ 24.0	$ 28.0
Senior Notes [Member]
Debt Instrument [Line Items]
Proceeds from issuance of debt				$ 2,200.0
Purchase of note principal			$ 700.0
Senior Notes [Member] \| Over LIBOR [Member]
Debt Instrument [Line Items]
Incremental increase in basis points resulting from downgrades						0.25%
Incremental decrease in basis points resulting from upgrades						0.25%
Increase in basis spread			1.75%
3.30% Senior Notes due January 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 350.0
Stated interest rate			5.05%	3.30%			3.30%
Maturity date, year and month				2018-01			2018-01
Percentage of face amount, sold to public				99.949%
Unamortized debt expense
Purchase of note principal	38.0
Debt repurchased	38.0
4.05% Senior Notes due January 2020 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 850.0
Stated interest rate			5.80%	4.05%	4.05%	4.05%	4.05%
Maturity date, year and month				2020-01		2020-01	2020-01
Percentage of face amount, sold to public				99.897%
Unamortized debt expense					$ 3.0	$ 3.0	$ 5.0
4.95% Senior Notes due January 2025 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 1,000.0
Stated interest rate			6.70%	4.95%	4.95%	4.95%	4.95%
Maturity date, year and month				2025-01		2025-01	2025-01
Percentage of face amount, sold to public				99.782%
Unamortized debt expense					$ 6.0	$ 6.0	$ 7.0
7.50% Senior Notes due February 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					7.50%	7.50%	7.50%
Maturity date, year and month						2018-02	2018-02
Net loss on extinguishment of debt		$ (1.0)
Unamortized debt expense
Purchase of note principal	187.0
Debt repurchased	187.0	$ 25.0
7.15% Senior Notes due June 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					7.15%	7.15%	7.15%
Maturity date, year and month						2018-06	2018-06
Unamortized debt expense
Purchase of note principal	26.0
Debt repurchased	$ 26.0
Maximum [Member] \| 3.30% Senior Notes due January 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					5.30%	5.30%
Maximum [Member] \| 4.05% Senior Notes due January 2020 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					6.05%	6.05%
Maximum [Member] \| 4.95% Senior Notes due January 2025 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					6.95%	6.95%