Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Options Issued To Officers, Directors, And Employees Under 2000 Stock Incentive Plan And 2005 Stock Plan) (Details) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
Dec. 15, 2018	Mar. 31, 2023
Shares
Shares, Options outstanding at beginning of period (in shares)		4,059,000
Shares, Grants (in shares)		326,000
Shares, Exercises (in shares)		(325,000)
Shares, Options vested and expected to vest (in shares)		3,896,000
Weighted-Average Exercise Price
Weighted Average Exercise Price, Options outstanding at beginning of period (in usd per share)		$ 62.59
Weighted Average Exercise Price, Grants (in usd per share)		71.07
Weighted Average Exercise Price, Exercises (in usd per share)		42.52
Weighted Average Exercise Price, Options outstanding at end of period (in usd per share)		64.92
Weighted Average Exercise Price, Options vested and expected to vest (in usd per share)		64.64
Weighted Average Exercise Price, Options exercisable (in usd per share)		$ 60.74
Weighted Average Remaining Contractual Life, Options vested and expected to vest at end of period		5 years 6 months 7 days
Weighted Average Remaining Contractual Life, Options exercisable		4 years 8 months 15 days
Aggregate Intrinsic Value, Options outstanding		$ 86,066
Aggregate Intrinsic Value, Options vested and expected to vest		85,167
Aggregate Intrinsic Value, Options exercisable		$ 77,350
Year End Stock Price (in dollars per share)		$ 85.42
2005 Stock Plan. [Member] \| Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested and exercisable (in shares)		3,059,000
Weighted average remaining contractual life		5 years 7 months 9 days
Shares
Shares, Options outstanding at end of period (in shares)		4,060,000
Weighted-Average Exercise Price
Weighted Average Remaining Contractual Life, Options outstanding		5 years 7 months 9 days
Performance-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares exercisable (in shares)		315,839
Performance-Based Stock Options [Member] \| Executive Officer [Member] \| December 15, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate Shares Granted at Target Award (in shares)	241,100
Shares exercisable (in shares)	158,700
Percentage Vested of Target Award	75.00%

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Options Issued To Officers, Directors, And Employees Under 2000 Stock Incentive Plan And 2005 Stock Plan) (Details) - USD ($)
$ / shares in Units, $ in Thousands

6 Months Ended

Dec. 15, 2018

Mar. 31, 2023

Shares

Shares, Options outstanding at beginning of period (in shares)

4,059,000

Shares, Grants (in shares)

326,000

Shares, Exercises (in shares)

(325,000)

Shares, Options vested and expected to vest (in shares)

3,896,000