Stockholders' Equity Rollforward (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	$ 430,539	$ 487,049	$ 573,203	$ 527,736
Comprehensive income	396,564	23,488	436,347	52,978
Cash dividends ($.085 and $.07 per share for the three months and $.255 and $.21 per share for the nine months ended September 30, 2018 and October 1, 2017, respectively)	(20,141)	(17,017)	(60,786)	(51,464)
Repurchases of common stock	(56,421)	(38,463)	(141,615)	(90,964)
Share-based compensation	4,810	4,984	14,401	16,356
Exercises of stock options	29,075	4,033	35,889	10,194
Vesting of restricted shares	(1,168)	(1,528)	(4,089)	(4,260)
Cumulative effect of new accounting principle in period of adoption	0	0	(70,210)	1,880
Other	60	49	178	139
Balance at end of period	$ 783,318	$ 462,595	$ 783,318	$ 462,595
Dividends per share	$ 0.085	$ 0.07	$ 0.255	$ 0.21
Deferred franchise fees	$ (92,522)		$ (92,522)		$ (10,881)
Deferred income taxes	(275,312)		(275,312)		(299,053)
Advertising funds restricted liabilities	(78,925)		(78,925)		$ (62,602)
Revenue recognition guidance
Increase (Decrease) in Stockholders' Equity
Deferred franchise fees	(85,561)		(85,561)
Deferred income taxes	21,996		21,996
Advertising funds restricted liabilities	$ (6,645)		$ (6,645)