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Employee Benefit Plans - Additional Information (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |  |  |
Maximum defer of compensation subject to statutory limitations, percentage | 70.00% |  |
Percentage of employer matching contributions condition, one | 100.00% |  |
Percentage of employee entitled to employer matching contribution condition, one | 3.00% |  |
Percentage of employer matching contributions condition, two | 50.00% |  |
Percentage of employee entitled to employer matching contribution condition, two | 2.00% |  |
Defined contribution plan, employer discretionary contribution amount | $ 16,200,000 | $ 15,100,000 | $ 14,900,000
Deferred compensation arrangement with individual, cash awards granted, percentage | 80.00% |  |
Deferred compensation on performance bonuses that eligible employee, percentage | 100.00% |  |
Defined contribution plan, employers matching contribution, annual vesting percentage | 100.00% |  |
Employee stock purchase plan shares authorized | 1,000,000 |  |
Employee stock purchase plan annual maximum payroll deduction | $ 25,000 |  |
Share-based compensation arrangement by share-based payment award, discount from market price, purchase date | 5.00% |  |
Stock issued during period, shares, employee stock purchase plans | 22,320 |  |
Stock issued during period, value, employee stock purchase plans, per share | $ 63.92 |  |
Employee stock purchase plan, number of shares available for grant | 702,506 |  |

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- Definition Represents employee stock purchase plan annual maximum payroll deduction. + References No definition available. + Details
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