Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 24, 2012	Jun. 26, 2011
Cash flows from operating activities:
Net earnings	$ 29,907	$ 25,534
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	30,267	22,574
Amortization	1,354	379
Loss on asset disposals and store closures	1,143	904
Deferred lease credits	1,618	1,568
Deferred income taxes	(2,245)	4,795
Stock-based compensation	3,919	5,952
Excess tax benefit from stock issuance	(289)	(211)
Change in operating assets and liabilities:
Trading securities	(534)	(246)
Accounts receivable	(4,484)	(2,643)
Inventory	281	(186)
Prepaid expenses	1,090	1,077
Other assets	(1,084)	(1,534)
Unearned franchise fees	(45)	(60)
Accounts payable	(177)	4,072
Income taxes	6,250	5,743
Accrued expenses	(234)	2,525
Net cash provided by operating activities	66,737	70,243
Cash flows for investing activities:
Acquisition of property and equipment	(44,438)	(55,159)
Purchase of marketable securities	(52,493)	(54,790)
Proceeds from marketable securities	39,998	63,597
Net cash used in investing activities	(56,933)	(46,352)
Cash flows for financing activities:
Issuance of common stock	1,117	867
Excess tax benefit from stock issuance	289	211
Tax payments for restricted stock units	(8,447)	(2,481)
Net cash used in financing activities	(7,041)	(1,403)
Effect of exchange rate changes on cash and cash equivalents	(46)	39
Net increase in cash and cash equivalents	2,717	22,527
Cash and cash equivalents at beginning of period	20,530	15,309
Cash and cash equivalents at end of period	$ 23,247	$ 37,836