Schedule of Estimated Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Jan. 01, 2017
2012 Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Principal Amount		$ 916,650
Fair Value		932,233
2015 Class Five-Year Notes [Member]
Debt Instrument [Line Items]
Principal Amount	$ 492,500	495,000
Fair Value	494,470	485,595
2015 Ten-Year Notes [Member]
Debt Instrument [Line Items]
Principal Amount	788,000	792,000
Fair Value	821,884	$ 765,864
2017 Five-Year Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Principal Amount	598,500
Fair Value	592,515
2017 Ten-Year Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Principal Amount	997,500
Fair Value	1,023,435
2017 Five-Year Floating Rate Notes [Member]
Debt Instrument [Line Items]
Principal Amount	299,250
Fair Value	$ 300,746