Amount Payable to Redeem the Notes, Percent of the Principal Amount

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- Definition

Debt Instrument Maturity Year

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- Definition

Discount Rate used to Compute the Remaining Scheduled Payments of Principal and Interest

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- Definition

Quarterly payments of interest.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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

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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.

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- Definition

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

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Weighted average interest rate of debt outstanding.

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No definition available.

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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- Definition

The fair value of notes issued in noncash investing and financing activities.

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The cash outflow for a borrowing supported by a written promise to pay an obligation.

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Credit and Other Debt Agreements - Note Purchase Agreements - Additional Information (Detail) - USD ($) $ in Millions								12 Months Ended
	Nov. 30, 2018	Jun. 24, 2018	Jan. 13, 2018	Aug. 04, 2017	Aug. 02, 2017	Jun. 27, 2017	Jun. 13, 2017	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Realized a cash gain on hedging transaction									$ 8.3
Fixed Rate of 4.34% Balloon Due June 13, 2028 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate								4.34%	4.34%
Debt instrument, due date								2028	2028
Fixed Rate of 4.44% Balloon Due June 13, 2030 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate								4.44%	4.44%
Debt instrument, due date								2030	2030
Fixed Rate of 4.59% Balloon Due June 13, 2033 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate								4.59%	4.59%
Debt instrument, due date								2033	2033
Fixed Rate of 4.69% Balloon Due June 13, 2038 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate								4.69%	4.69%
Debt instrument, due date								2038	2038
Floating Interest Rate of 1.40% LIBOR Plus Balloon Due June 13, 2024 [Member]
Debt Instrument [Line Items]
Quarterly payments of interest								$ 50.0
Debt instrument, interest rate								1.40%	1.40%
Debt instrument, interest rate description								90 day LIBOR plus	90 day LIBOR plus
Debt instrument, due date								2024	2024
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 500.0
Realized a cash gain on hedging transaction								$ 2.9
Amount payable to redeem the notes, percent of the principal amount								100.00%
Discount rate used to compute the remaining scheduled payments of principal and interest								U.S. Treasury yield plus 0.5%
Note Purchase Agreements [Member] \| Floating Interest Rate 4.39% LIBOR Due February 4, 2019 [Member]
Debt Instrument [Line Items]
Quarterly payments of interest									$ 50.0
Debt instrument, interest rate									4.39%
Debt instrument, maturity date									Feb. 04, 2019
Debt instrument, interest rate description									Three-month LIBOR
Note Purchase Agreements [Member] \| Fixed Rate of 4.34% Balloon Due June 13, 2028 [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 125.0
Debt instrument, interest rate								4.34%
Debt instrument, due date								2028
Debt instrument, interest raet effect to hedging gains								4.00%
Note Purchase Agreements [Member] \| Fixed Rate of 4.44% Balloon Due June 13, 2030 [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 125.0
Debt instrument, interest rate								4.44%
Debt instrument, due date								2030
Note Purchase Agreements [Member] \| Fixed Rate of 4.59% Balloon Due June 13, 2033 [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 125.0
Debt instrument, interest rate								4.59%
Debt instrument, due date								2033
Note Purchase Agreements [Member] \| Fixed Rate of 4.69% Balloon Due June 13, 2038 [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 75.0
Debt instrument, interest rate								4.69%
Debt instrument, due date								2038
Note Purchase Agreements [Member] \| Floating Interest Rate of 1.40% LIBOR Plus Balloon Due June 13, 2024 [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 50.0
Debt instrument, interest rate								1.40%
Debt instrument, interest rate description								90 day LIBOR plus
Debt instrument, due date								2024
Note Purchase Agreements [Member] \| Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold	$ 50.0	$ 50.0
Note Purchase Agreements [Member] \| Senior Unsecured Notes [Member] \| Private Placement [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50.0	$ 500.0	$ 98.0	$ 300.0	$ 250.0	$ 648.0
Note Purchase Agreements [Member] \| Senior Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold			$ 450.0						$ 598.0
Weighted average interest rate of notes			4.42%						4.04%
Quarterly payments of interest								$ 50.0
Debt instrument, interest rate								4.14%
Debt instrument, maturity date								Feb. 04, 2019
Debt instrument, interest rate description								Three-month LIBOR
Note Purchase Agreements [Member] \| Senior Fixed Rate Notes [Member] \| Weighted Average [Member]
Debt Instrument [Line Items]
Weighted average maturity of notes								13 years 7 months 6 days	11 years 7 months 6 days
Note Purchase Agreements [Member] \| 6.44% Senior Notes, Series B [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 300.0
Repayment of notes									$ 300.0
Debt instrument, maturity date									Aug. 03, 2017