Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) director $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares
Unrecognized compensation cost and vesting period
Unrecognized compensation costs related to unvested stock-based compensation arrangements | $	$ 17,300,000
Weighted-average period for recognition of unrecognized stock-based compensation expense	2 years 2 months 12 days
Other disclosures
Shares issued and committed to issue | shares	13,400	12,600	7,000
Shares committed to be issued | shares	6,900	7,400	4,000
Shares expected to be settled In cash | shares	6,500	5,200	3,000
Stock-based compensation expense recognized in operating expenses | $	$ (15,036,000)	$ (11,384,000)	$ (9,480,000)
Requisite service period for options to vest	3 years
Tax benefit of stock-based compensation expense in provision for income taxes | $	$ 3,787,000	2,859,000	2,330,000
Share-based Payment Arrangement, Expense, after Tax | $	11,249,000	8,525,000	7,150,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value | $	$ 15,701,000	$ 21,921,000	16,760,000
Weighted average grant date, period	60 days
Vesting period	4 years
Restricted Stock Units
Restricted stock unit activity
Outstanding at the beginning of the period (in shares) | shares	351,000
Awarded (in shares) | shares	168,000
Vested (in shares) | shares	(162,000)
Forfeited (in shares) | shares	(13,000)
Outstanding at the end of the period (in shares) | shares	344,000	351,000
Outstanding and expected to vest at the end of the period (in shares) | shares	474,000
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 66.13
Awarded (in dollars per share) | $ / shares	93.26
Vested (in dollars per share) | $ / shares	60.30
Forfeited (in dollars per share) | $ / shares	81.50
Outstanding at the end of the period (in dollars per share) | $ / shares	81.33	$ 66.13
Outstanding and expected to vest at the end of the period (in dollars per share) | $ / shares	$ 78.45
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars) | $	$ 47,721,000	$ 33,188,000
Outstanding and expected to vest at end of the period (in dollars) | $	$ 65,984,000
Closing price per share (in dollars per share) | $ / shares	$ 139.07
Total intrinsic value of awards vested (in dollars) | $	$ 15,700,000	$ 21,900,000	16,700,000
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 66.13
Forfeited (in dollars per share) | $ / shares	81.50
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 81.33	$ 66.13
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars) | $	$ 47,721,000	$ 33,188,000
Other disclosures
Stock-based compensation expense recognized in operating expenses | $	$ (756,000)
Vesting period	4 years
Phantom Share Units (PSUs)
Other disclosures
Vesting period	3 years
2011 Plan | Non-Qualified Stock Options
Stock-Based Compensation
Maximum common stock shares that may be issued under plan | shares	16,300,000
Stock Bonus Plan | Restricted Stock Units
Aggregate Intrinsic Value
Total intrinsic value of awards vested (in dollars) | $	$ 1,700,000	$ 1,200,000	$ 800,000
Independent directors | Restricted Stock Units
Aggregate Intrinsic Value
Number Of Directors | director	7
Other disclosures
Deferred Compensation Arrangement with Individual, Allocated Share-based Compensation Expense | $	$ 690,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted | shares	6,601
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares	$ 100.33
Employees | Restricted Stock Units
Restricted stock unit activity
Awarded (in shares) | shares	161,643
Weighted-Average Exercise Price
Awarded (in dollars per share) | $ / shares	$ 100.93