Debt - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2020	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 17, 2020	Sep. 09, 2020	Jun. 30, 2020	May 04, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 10, 2012
Debt Instrument [Line Items]
Operating Lease, Expense			$ 7,689,000	$ 8,829,000	$ 23,542,000	$ 24,776,000
Finance Lease, Right-of-Use Asset, Amortization			327,000	125,000	874,000	146,000
Finance Lease, Interest Expense			70,000	25,000	170,000	30,000
Short-term Lease Payments			5,625,000	5,530,000	18,236,000	16,775,000
Stockholders' Equity Attributable to Parent	$ 2,918,993,000		2,918,993,000	2,371,457,000	2,918,993,000	2,371,457,000			$ 2,612,412,000		$ 2,341,244,000	$ 2,119,439,000	$ 1,808,562,000
Net income			256,466,000	223,787,000	596,244,000	622,402,000
Treasury Stock, Value, Acquired, Cost Method				(61,063,000)	(216,582,000)	(365,542,000)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition				20,770,000	35,565,000	58,680,000
APIC, Share-based Payment Arrangement, Recognition and Exercise			36,476,000	68,524,000	162,522,000	247,355,000
Stock Issued During Period, Value, Stock Options Exercised			0	0	0	0
Lease, Cost			13,711,000	14,509,000	42,822,000	41,727,000
Operating cash flows from operating leases			7,339,000	5,757,000	20,733,000	19,515,000
Operating cash flows from finance leases			70,000	46,000	170,000	30,000
Financing cash flows from finance leases			253,000	190,000	665,000	116,000
Operating leases			1,806,000	5,532,000	7,491,000	11,546,000
Finance leases			9,056,000	1,065,000	9,496,000	6,369,000
Deferred Compensation Activity Adjustments					0	0
Common Stock [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	206,000		206,000	206,000	206,000	206,000			206,000		206,000	206,000	206,000
Additional Paid-In-Capital [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	2,188,207,000		2,188,207,000	2,020,180,000	2,188,207,000	2,020,180,000			2,151,623,000		2,055,407,000	1,962,156,000	1,820,223,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition				20,770,000	35,565,000	58,680,000
APIC, Share-based Payment Arrangement, Recognition and Exercise			36,476,000	68,524,000	162,522,000	247,355,000
Stock Issued During Period, Value, Stock Options Exercised			(13,531,000)	(31,270,000)	(65,287,000)	(106,078,000)
Retained Earnings [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	8,506,116,000		8,506,116,000	7,653,735,000	8,506,116,000	7,653,735,000			8,249,650,000		7,909,872,000	7,429,948,000	7,031,333,000
Net income			256,466,000	223,787,000	596,244,000	622,402,000
Treasury Stock [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	(7,775,536,000)		(7,775,536,000)	(7,302,664,000)	(7,775,536,000)	(7,302,664,000)			(7,789,067,000)		(7,624,241,000)	(7,272,871,000)	(7,043,200,000)
Treasury Stock, Value, Acquired, Cost Method				(61,063,000)	(216,582,000)	(365,542,000)
Stock Issued During Period, Value, Stock Options Exercised			13,531,000	31,270,000	65,287,000	106,078,000
Deferred Compensation Trust [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	(16,710,000)		(16,710,000)	(16,912,000)	(16,710,000)	(16,912,000)			(16,710,000)		(16,912,000)	(16,912,000)	(16,937,000)
Deferred Compensation Activity Adjustments					202,000	25,000
Deferred Compensation Liability [Member]
Debt Instrument [Line Items]
Stockholders' Equity Attributable to Parent	16,710,000		16,710,000	$ 16,912,000	16,710,000	16,912,000			$ 16,710,000		$ 16,912,000	$ 16,912,000	$ 16,937,000
Deferred Compensation Activity Adjustments					(202,000)	$ (25,000)
Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior notes principal amount	$ 600,000,000		$ 600,000,000		$ 600,000,000
Senior notes interest rate	3.95%		3.95%		3.95%									3.95%
Frequency of senior notes payment					semi-annually in arrears on March 15 and September 15
Senior notes effective interest rate	3.97%		3.97%		3.97%
Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum loan borrowing capacity	$ 200,000,000		$ 200,000,000		$ 200,000,000
Increase in commitment available					300,000,000
Debt outstanding	0		0		0
Credit Agreement [Member] | Revolving Credit Facility [Member] | Sublimit for Issuance of Letters of Credit [Member]
Debt Instrument [Line Items]
Maximum loan borrowing capacity	100,000,000		100,000,000		100,000,000
Letters of credit outstanding	11,450,000		11,450,000		11,450,000
Credit Agreement [Member] | Revolving Credit Facility [Member] | Sublimit for Swing Line Commitment [Member]
Debt Instrument [Line Items]
Maximum loan borrowing capacity	25,000,000		25,000,000		25,000,000
Repurchase Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum loan borrowing capacity	150,000,000		150,000,000		150,000,000
Debt outstanding	$ 0		$ 0		$ 0
Senior Notes Due Two Thousand Thirty [Member]
Debt Instrument [Line Items]
Senior notes principal amount							$ 50,000,000	$ 250,000,000		$ 600,000,000
Senior notes interest rate	3.00%		3.00%		3.00%					3.00%
Frequency of senior notes payment					semi-annually in arrears on May 15 and November 15
Senior notes effective interest rate							2.00%			3.02%
Proceeds from Debt, Net of Issuance Costs	$ 323,900,000	$ 595,300,000
Proceeds from Debt, Net of Issuance Costs	$ 323,900,000	$ 595,300,000