Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($)						3 Months Ended		6 Months Ended		37 Months Ended	41 Months Ended
	Apr. 24, 2018	Jan. 24, 2018	Dec. 15, 2017	Dec. 15, 2016	Dec. 15, 2015	Mar. 30, 2018	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017	Oct. 31, 2010	Mar. 28, 2014	Sep. 29, 2017	Jan. 25, 2017	Oct. 31, 2014	Feb. 29, 2012	Jul. 31, 2011	Jul. 31, 2010	Nov. 30, 2009
Stockholders' Equity And Stock-Based Compensation [Line Items]
Options outstanding to purchase												8,741,000
Year end stock price								$ 63.56
Percentage of vesting per year										50.00%
Common stock, dividends declared (in dollars per share)						$ 0.16	$ 0.14	$ 0.32	$ 0.28
Remaining authorization to purchase additional shares						$ 117,000,000		$ 117,000,000
Authorization Amount						1,300,000,000		1,300,000,000										$ 250,000,000
Subsequent Event [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Common stock, dividends declared (in dollars per share)	$ 0.16	$ 0.16
Employee Stock Option [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock options expected to vest						$ 34,000,000		$ 34,000,000
Employee stock options expected to be recognized over a weighted-average period								2 years 5 months
Performance-Based Stock Options [Member] | Executive Officer [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Shares exercisable (in shares)						981,121		981,121
Percentage Of Target Award								125.00%
Options outstanding to purchase						784,898		784,898
Performance-Based Stock Options [Member] | Executive Officer [Member] | Awarded Fiscal 2018 [Member] [Domain]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Shares exercisable (in shares)			330,000
Percentage Of Target Award			125.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			264,000
Performance-Based Stock Options [Member] | Executive Officer [Member] | Awarded Fiscal 2016 [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Shares exercisable (in shares)					419,623
Percentage Of Target Award					125.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures					335,699
Performance-Based Stock Options [Member] | Executive Officer [Member] | Awarded Fiscal 2017 [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Shares exercisable (in shares)				345,248
Percentage Of Target Award				125.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures				276,199
Restricted Stock Units (RSUs) [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock options expected to vest						$ 108,300,000		$ 108,300,000
Employee stock options expected to be recognized over a weighted-average period								2 years 8 months 9 days
Restricted Stock Units (RSUs) [Member] | Employees and Officers [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period								4 years
Restricted Stock Units (RSUs) [Member] | Awards Granted Prior to November 2010 [Member] | Directors [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period										3 years	1 year
Restricted Stock Units (RSUs) [Member] | Awards Granted After November 2010 [Member] | Directors [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period										2 years
Awards Granted Under 2005 Stock Plan Prior To February 2011 [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Terms for issuance of stock								2
Awards Granted Under 2005 Stock Plan From February 2011 [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Terms for issuance of stock								1.6
Employee Stock Purchase Plan [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Percentage of compensation withheld by employees to purchase common stock								10.00%
Common stock purchase price determined over percentage of closing price								15.00%
Additional Stock Approved [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Authorization Amount													$ 200,000,000	$ 200,000,000	$ 100,000,000	$ 250,000,000	$ 300,000,000
Class A Common Stock [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Common stock, shares authorized (shares)						500,000,000		500,000,000				500,000,000
Common stock, shares issued (shares)						61,364,751		61,364,751				59,281,837
Common stock, shares outstanding (shares)						61,364,751		61,364,751				59,281,837
Class A Common Stock [Member] | 2005 Stock Plan. [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Shares authorized under plan						46,000,000		46,000,000
Options outstanding to purchase						7,920,000		7,920,000
Weighted average remaining contractual life								7 years
Options vested and exercisable						4,015,000		4,015,000
Class A Common Stock [Member] | Employee Stock Purchase Plan [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Maximum value of common stock available for eligible employees								$ 25,000
Maximum number of common stock available for eligible employees								1,000
Purchase period								6 months
Look back commencement period								1 year
Class B Common Stock [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Common stock, shares authorized (shares)						500,000,000		500,000,000				500,000,000
Common stock, shares issued (shares)						42,733,038		42,733,038				42,873,597
Common stock, shares outstanding (shares)						42,733,038		42,733,038				42,873,597
Options Granted Prior To June 2008 [Member] | Employee Stock Option [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period								4 years
Options expiration period								10 years
Options Granted From June Two Thousand Eight Member | Employee Stock Option [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period								36 months
Percentage of stock option becoming exercisable subjected to date of grant								25.00%