Fair Value Measurements (Summary Of Assets And Liabilities Measured at Fair Value) (Detail) - USD ($) $ in Thousands	Mar. 27, 2016	Dec. 31, 2015	Mar. 29, 2015
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	$ 18,600	$ 17,700	$ 14,500
Fair Value, Measurements, Recurring [Member] | Balance [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	531,823	555,910	975,411
Investments, Fair Value Disclosure	83,689	81,448	94,886
Derivative Asset, Current	3,651	16,235	49,290
Assets, Fair Value Disclosure	619,163	653,593	1,119,587
Derivatives, liabilities	3,176	1,300	1,886
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	426,700	390,706	510,090
Investments, Fair Value Disclosure	38,567	36,256	37,667
Derivative Asset, Current	0	0	0
Assets, Fair Value Disclosure	465,267	426,962	547,757
Derivatives, liabilities	0	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	105,123	165,204	465,321
Investments, Fair Value Disclosure	45,122	45,192	57,219
Derivative Asset, Current	3,651	16,235	49,290
Assets, Fair Value Disclosure	153,896	226,631	571,830
Derivatives, liabilities	3,176	1,300	1,886
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0	0
Investments, Fair Value Disclosure	0	0	0
Derivative Asset, Current	0	0	0
Assets, Fair Value Disclosure	0	0	0
Derivatives, liabilities	0	0	0
Fair value, adjustment [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	$ 6,500	$ 8,600	$ 3,500