Share-Based Compensation and Benefit Plans (Stock Option Activity) (Details) - Stock option [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-Based Compensation and Benefit Plans
Compensation expense for share-based compensation	$ 18,435	$ 18,044	$ 16,521
Income tax benefit from compensation expense for share-based compensation	4,620	4,436	4,093
Total intrinsic value of options exercised	79,451	117,489	156,327
Cash received from the exercise of stock options	$ 46,282	$ 46,106	$ 61,403
Weighted-average grant date fair value of options awarded	$ 106.76	$ 105.37	$ 76.57
Weighted-average remaining contractual life of options currently exercisable	4 years 6 months	4 years 7 months 6 days	4 years 4 months 24 days
Employee stock option [Member]
Share-Based Compensation and Benefit Plans
Weighted-average remaining contractual life of options currently exercisable	4 years 6 months

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of cash inflow from issuance of shares under share-based payment arrangement. Includes, but is not limited to, option exercised.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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