CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Cash flows from operating activities:
Net income	$ 562,354	$ 532,357	$ 422,599
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	195,978	177,351	165,834
Gain on disposition of property and equipment	(297)	(567)	460
Share-based compensation expense	31,136	28,921	29,202
Deferred income taxes	6,760	11,887	26,724
Change in assets and liabilities
Inventories	(13,239)	(136,334)	(83,552)
Prepaid expenses and other current assets	13,582	(26,195)	2,305
Accounts payable	23,055	43,413	57,046
Accrued employee compensation	(14,291)	22,373	6,427
Other accrued expenses	10,351	36,406	(10,338)
Income taxes	8,327	(8,355)	4,210
Other	(12,000)	13,137	10,533
Net cash provided by operating activities	811,716	694,394	631,450
Cash flows from investing activities:
Capital expenditures	(217,450)	(278,530)	(250,401)
Proceeds from sale of property and equipment	2,489	2,216	11,220
Acquisition of Petsense, net of cash acquired	0	0	1,225
Net cash used in investing activities	(214,961)	(276,314)	(237,956)
Cash flows from financing activities:
Borrowings under debt facilities	1,002,000	1,193,500	1,180,000
Repayments under debt facilities	(1,013,250)	(1,212,250)	(1,027,500)
Debt issuance costs	0	(346)	(599)
Principal payments under finance lease liabilities	(3,708)	(3,246)	(2,446)
Repurchase of shares to satisfy tax obligations	(3,818)	(1,367)	(816)
Repurchase of common stock	(533,319)	(349,776)	(369,403)
Net proceeds from issuance of common stock	115,981	79,643	16,330
Cash dividends paid to stockholders	(162,699)	(147,087)	(133,828)
Net cash used in financing activities	(598,813)	(440,929)	(338,262)
Net change in cash and cash equivalents	(2,058)	(22,849)	55,232
Cash and cash equivalents at beginning of year	86,299	109,148	53,916
Cash and cash equivalents at end of year	84,241	86,299	109,148
Cash paid during the year for:
Income taxes	144,377	146,918	219,081
Supplemental disclosures of non-cash activities [Abstract]
Non-cash accruals for construction in progress	7,924	3,001	8,647
Interest Paid, Excluding Capitalized Interest, Operating Activities	19,146	18,069	10,481
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	2,084,880	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	365,233	0	0
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 5,217	$ 0	$ 11,395