Summary of Significant Accounting Policies - Composition of Underlying Assets Comprising Company's Deferred Compensation Plans Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	$ 445,739	$ 398,442
Quoted Prices in Active Markets for Identical Assets (Level 1)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	445,739	398,442
Significant Other Observable Inputs (Level 2)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Significant Unobservable Inputs (Level 3)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Money market funds
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	151,171	141,295
Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	151,171	141,295
Money market funds | Significant Other Observable Inputs (Level 2)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Money market funds | Significant Unobservable Inputs (Level 3)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - bond
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	26,717	28,451
Mutual funds - bond | Quoted Prices in Active Markets for Identical Assets (Level 1)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	26,717	28,451
Mutual funds - bond | Significant Other Observable Inputs (Level 2)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - bond | Significant Unobservable Inputs (Level 3)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	202,707	170,469
Mutual funds - stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	202,707	170,469
Mutual funds - stock | Significant Other Observable Inputs (Level 2)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - stock | Significant Unobservable Inputs (Level 3)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - blend
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	65,144	58,227
Mutual funds - blend | Quoted Prices in Active Markets for Identical Assets (Level 1)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	65,144	58,227
Mutual funds - blend | Significant Other Observable Inputs (Level 2)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	0	0
Mutual funds - blend | Significant Unobservable Inputs (Level 3)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation trust assets	$ 0	$ 0