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Credit and Other Debt Agreements - Note Purchase Agreements - Additional Information (Detail) - USD ($) $ in Millions									12 Months Ended
	Jan. 30, 2020	Dec. 02, 2019	Jun. 12, 2019	Feb. 13, 2019	Nov. 30, 2018	Jun. 24, 2018	Jun. 13, 2018	Jan. 13, 2018	Dec. 31, 2019	Dec. 31, 2018
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]
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
Fixed Rate of 4.72%, Balloon due February 13, 2024 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 100.0
Debt instrument, interest rate									4.72%	4.72%
Debt instrument, due date									2024	2024
Fixed Rate of 4.85%, Balloon due February 13, 2026 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 140.0
Debt instrument, interest rate									4.85%	4.85%
Debt instrument, due date									2026	2026
Fixed Rate of 5.04%, Balloon due February 13, 2029 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 100.0
Debt instrument, interest rate									5.04%	5.04%
Debt instrument, due date									2029	2029
Fixed Rate of 5.14%, Balloon due March 13, 2031 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 180.0
Debt instrument, interest rate									5.14%	5.14%
Debt instrument, due date									2031	2031
Fixed Rate of 5.29%, balloon due March 13, 2034 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 40.0
Debt instrument, interest rate									5.29%	5.29%
Debt instrument, due date									2034	2034
Fixed Rate of 5.45%, balloon due March 13, 2039 [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 40.0
Debt instrument, interest rate									5.45%	5.45%
Debt instrument, due date									2039	2039
Fixed Rate of 3.75% senior notes due in 2027
Debt Instrument [Line Items]
Notes issued and sold									$ 30.0
Debt instrument, interest rate									3.75%
Debt instrument, due date									2027
Fixed Rate of 3.99% senior notes due in 2030
Debt Instrument [Line Items]
Notes issued and sold									$ 341.0
Debt instrument, interest rate									3.99%
Debt instrument, due date									2030
Fixed Rate of 4.09% senior notes due in 2032
Debt Instrument [Line Items]
Notes issued and sold									$ 69.0
Debt instrument, interest rate									4.09%
Debt instrument, due date									2032
Fixed Rate of 4.24% senior notes due in 2035
Debt Instrument [Line Items]
Notes issued and sold									$ 79.0
Debt instrument, interest rate									4.24%
Debt instrument, due date									2035
Fixed Rate of 4.49% senior notes due in 2040
Debt Instrument [Line Items]
Notes issued and sold									$ 56.0
Debt instrument, interest rate									4.49%
Debt instrument, due date									2040
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Notes issued and sold									$ 500.0
Realized a cash gain on hedging transaction			$ 5.2	$ 1.2					$ 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] | Subsequent Event [Member]
Debt Instrument [Line Items]
Realized a cash gain on hedging transaction	$ 8.9
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										3.14%
Debt instrument, maturity date										Feb. 03, 2020
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
Quarterly payments of interest									$ 50.0	$ 50.0
Debt instrument, interest rate description									90 day LIBOR plus
Debt instrument, interest rate									1.40%
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				600.0		$ 50.0	$ 500.0
Note Purchase Agreements [Member] | Senior Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold								$ 450.0
Weighted average interest rate of notes								4.42%
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
Note Purchase Agreements [Member] | Fixed Rate Senior Unsecured Notes [Member] | Private Placement [Member] | Tranche One Member
Debt Instrument [Line Items]
Notes issued and sold				340.0
Note Purchase Agreements [Member] | Fixed Rate Senior Unsecured Notes [Member] | Private Placement [Member] | Tranche Two Member
Debt Instrument [Line Items]
Notes issued and sold				$ 260.0
Note Purchase Agreements [Member] | Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted average interest rate of notes				5.04%
Note Purchase Agreements [Member] | Unsecured Notes [Member] | Private Placement [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50.0	$ 175.0
Weighted average interest rate of notes		3.48%
Debt instrument, interest rate			4.48%
Debt instrument, due date			2034
Note Purchase Agreements [Member] | Unsecured Notes [Member] | Private Placement [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Notes issued and sold	$ 575.0
Weighted average maturity of notes	11 years 8 months 12 days
Weighted average interest rate of notes	4.23%
Note Purchase Agreements [Member] | Unsecured Notes [Member] | Private Placement [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Weighted average maturity of notes				10 years 1 month 6 days
Note Purchase Agreements [Member] | Series K Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold			$ 50.0
Weighted average interest rate of notes			4.68%
Note Purchase Agreements [Member] | Series C Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50.0

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