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

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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

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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- Definition

Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

+ References

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- Definition

Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

+ References

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- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

+ Details

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- Definition

Amount, after accumulated amortization, of debt issuance costs classified as current. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Parent Company Debt Schedule (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument
Long-term Debt, Excluding Current Maturities	$ 2,971.3			$ 2,738.4
Debt Instrument, Unamortized Premium (Discount), Net	9.6			9.7
Debt Issuance Costs, Noncurrent, Net	(30.8)			(24.4)
Current Maturities of Long-term Debt	0.0			199.9
Debt Issuance Costs, Current, Net	0.0			(0.1)
Fair Value Hedge Adjustment, LT Debt
Debt Instrument
Long-term Debt, Excluding Current Maturities	(5.1)			(4.5)
Parent Company
Debt Instrument
Long-term Debt, Excluding Current Maturities	2,831.3			2,538.4
Debt Instrument, Unamortized Premium (Discount), Net	9.6			9.7
Debt Issuance Costs, Noncurrent, Net	(30.8)			(24.4)
Current Maturities of Long-term Debt	0.0			199.9
Debt Issuance Costs, Current, Net	0.0			(0.1)
Debt, Long-term and Short-term, Combined Amount	2,831.3			2,738.3
Parent Company \| Fair Value Hedge Adjustment, LT Debt
Debt Instrument
Long-term Debt, Excluding Current Maturities	$ (5.1)			(4.5)
Notes Issued in 1998 with 2028 Maturity Date \| Senior Notes
Debt Instrument
Year of Maturity	Dec. 31, 2028
Long-term Debt, Excluding Current Maturities	$ 365.8			365.8
Notes Issued in 1998 with 2028 Maturity Date \| Parent Company \| Senior Notes
Debt Instrument
Year of Maturity	Dec. 31, 2028
Long-term Debt, Excluding Current Maturities	$ 365.8			365.8
Notes Issued in 1998 with 2028 Maturity Date \| Minimum \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			6.75%
Notes Issued in 1998 with 2028 Maturity Date \| Minimum \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			6.75%
Notes Issued in 1998 with 2028 Maturity Date \| Maximum \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			7.25%
Notes Issued in 1998 with 2028 Maturity Date \| Maximum \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			7.25%
Notes Issued in 2002 \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			7.375%
Year of Maturity	Dec. 31, 2032
Long-term Debt, Excluding Current Maturities	$ 39.5			39.5
Notes Issued in 2002 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			7.375%
Year of Maturity	Dec. 31, 2032
Long-term Debt, Excluding Current Maturities	$ 39.5			39.5
Notes Issued in 2010 \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			5.625%
Year of Maturity	Dec. 31, 2020
Long-term Debt, Excluding Current Maturities	$ 400.0			400.0
Notes Issued in 2010 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			5.625%
Year of Maturity	Dec. 31, 2020
Long-term Debt, Excluding Current Maturities	$ 400.0			400.0
Notes Issued in 2012 and 2016 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			5.75%
Year of Maturity	Dec. 31, 2042
Long-term Debt, Excluding Current Maturities	$ 500.0			500.0
Notes Issued in 2014 \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			4.00%
Year of Maturity	Dec. 31, 2024
Long-term Debt, Excluding Current Maturities	$ 350.0			350.0
Notes Issued in 2014 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			4.00%
Year of Maturity	Dec. 31, 2024
Long-term Debt, Excluding Current Maturities	$ 350.0			350.0
Notes Issued in 2015 \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			3.875%
Year of Maturity	Dec. 31, 2025
Long-term Debt, Excluding Current Maturities	$ 275.0			275.0
Notes Issued in 2015 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			3.875%
Year of Maturity	Dec. 31, 2025
Long-term Debt, Excluding Current Maturities	$ 275.0			275.0
Notes Issued in 2016 \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			3.00%
Year of Maturity	May 15, 2021
Long-term Debt, Excluding Current Maturities	$ 350.0			350.0
Notes Issued in 2016 \| Parent Company \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			3.00%
Year of Maturity	Dec. 31, 2021
Long-term Debt, Excluding Current Maturities	$ 350.0			350.0
Notes Issued 1990 to 1996 \| Medium-term Notes
Debt Instrument
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2023
Debt Instrument, Maturity Date Range, End	Dec. 31, 2028
Long-term Debt, Excluding Current Maturities	$ 50.8			50.8
Notes Issued 1990 to 1996 \| Parent Company \| Medium-term Notes
Debt Instrument
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2023
Debt Instrument, Maturity Date Range, End	Dec. 31, 2028
Long-term Debt, Excluding Current Maturities	$ 50.8			50.8
Notes Issued 1990 to 1996 \| Minimum \| Medium-term Notes
Debt Instrument
Stated Interest Rate of Debt			7.00%
Notes Issued 1990 to 1996 \| Minimum \| Parent Company \| Medium-term Notes
Debt Instrument
Stated Interest Rate of Debt			7.00%
Notes Issued 1990 to 1996 \| Maximum \| Medium-term Notes
Debt Instrument
Stated Interest Rate of Debt			7.19%
Notes Issued 1990 to 1996 \| Maximum \| Parent Company \| Medium-term Notes
Debt Instrument
Stated Interest Rate of Debt			7.19%
Notes Issued in 1998 with 2038 Maturity Date \| Junior Subordinated Debt
Debt Instrument
Stated Interest Rate of Debt		7.405%	7.405%
Year of Maturity	Dec. 31, 2038
Long-term Debt, Excluding Current Maturities	$ 226.5			226.5
Notes Issued in 1998 with 2038 Maturity Date \| Parent Company \| Junior Subordinated Debt
Debt Instrument
Stated Interest Rate of Debt		7.405%	7.405%
Year of Maturity	Dec. 31, 2038
Long-term Debt, Excluding Current Maturities	$ 226.5			226.5
Notes Issued in 2018 with a 2058 Maturity Date \| Junior Subordinated Debt
Debt Instrument
Stated Interest Rate of Debt			6.25%
Year of Maturity	Dec. 31, 2058
Long-term Debt, Excluding Current Maturities	$ 300.0			0.0
Notes Issued in 2018 with a 2058 Maturity Date \| Parent Company \| Junior Subordinated Debt
Debt Instrument
Stated Interest Rate of Debt			6.25%
Year of Maturity	Dec. 31, 2058
Long-term Debt, Excluding Current Maturities	$ 300.0			0.0
Notes Issued in 1998 with 2018 Maturity Date \| Parent Company
Debt Instrument
Stated Interest Rate of Debt			7.00%
Current Maturities of Long-term Debt	$ 200.0
Notes Issued in 1998 with 2018 Maturity Date \| Senior Notes
Debt Instrument
Stated Interest Rate of Debt			7.00%
Year of Maturity	Dec. 31, 2018
Current Maturities of Long-term Debt	$ 0.0			200.0
Notes Issued in 1998 with 2018 Maturity Date \| Senior Notes \| Parent Company
Debt Instrument
Stated Interest Rate of Debt			7.00%
Year of Maturity	Jul. 15, 2018
Current Maturities of Long-term Debt	$ 0.0			$ 200.0