Borrowings - Narrative (Details)					12 Months Ended
	May 27, 2020 USD ($)	Apr. 29, 2020 USD ($)	Jun. 23, 2015 USD ($)	Dec. 09, 2011 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 31, 2019 USD ($)	Jun. 13, 2016 USD ($)	Dec. 06, 2010
Line of Credit Facility [Line Items]
Less unaccreted debt discount					$ 949,000	$ 387,000
Interest					35,152,000	36,683,000	$ 36,327,000
Amount to be recognized from hedged transactions within 12 months, approximate					(2,500,000)
Credit facility, term			5 years
Balance outstanding					1,050,215,000	850,622,000
Short-term borrowings					$ 88,000	$ 388,000
For 12 Months in Connection with Certain Acquisitions
Line of Credit Facility [Line Items]
Leverage ratio					4.00
Line of Credit
Line of Credit Facility [Line Items]
Current borrowing capacity			$ 700,000,000
Revolving facility, extension term			1 year
Revolving Credit Facility
Line of Credit Facility [Line Items]
Current borrowing capacity								$ 800,000,000
Aggregate lending commitments								$ 400,000,000
Applicable margin					1.00%
Weighted average interest rate					1.24%
Minimum
Line of Credit Facility [Line Items]
Required percent for prepayment amount of aggregate principal amount									5.00%
Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Applicable leverage ratio					0.00%
Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Applicable leverage ratio					1.275%
3.00% Senior Notes, due May 2030
Line of Credit Facility [Line Items]
Stated interest rate					3.00%
4.50% Senior Notes, due December 2020
Line of Credit Facility [Line Items]
Stated interest rate						4.50%				4.50%
3.20% Senior Notes, due June 2023
Line of Credit Facility [Line Items]
Stated interest rate					3.20%	3.20%
3.37% Senior Notes, due June 2025
Line of Credit Facility [Line Items]
Stated interest rate					3.37%	3.37%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Balance outstanding					$ 0	$ 0
Outstanding letters of credit					7,200,000
Revolving facility, amount available to borrow					$ 792,800,000
Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Interest coverage ratio					3.0
Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Leverage ratio					3.50
4.20% Senior Notes, due December 2021
Line of Credit Facility [Line Items]
Stated interest rate				4.20%	4.20%	4.20%
Principal amount of private placement				$ 350,000,000.0
Net proceeds from debt offering				346,200,000
Debt offering initial discount				900,000
Debt offering underwriting commission				2,300,000
Estimated offering expenses				600,000
Outstanding repayment of indebtedness				$ 306,000,000.0
Contingent percentage of principal amount plus accrued and unpaid interest				101.00%
Short-term borrowings					$ 350,000,000.0
Senior Notes | Maximum
Line of Credit Facility [Line Items]
Limitation of outstanding principal of higher preference debt as percent of consolidated assets									15.00%
Senior Notes | 3.00% Senior Notes, due May 2030
Line of Credit Facility [Line Items]
Debt instrument face amount		$ 500,000,000.0
Stated interest rate		3.00%			3.00%
Proceeds from debt		$ 494,400,000
Less unaccreted debt discount		900,000
Underwriting commission		3,300,000
Offering expenses		$ 1,400,000
Redemption price, percentage		101.00%
Balance outstanding					$ 500,000,000	$ 0
Senior Notes | 3.00% Senior Notes, due May 2030 | Minimum
Line of Credit Facility [Line Items]
Percent of outstanding amount owned for decision making		25.00%
Senior Notes | 4.50% Senior Notes, due December 2020
Line of Credit Facility [Line Items]
Stated interest rate					4.50%
Extinguishment of debt	$ 300,000,000.0	$ 300,000,000.0
Redemption premium	6,800,000
Interest	6,100,000
Amount to be recognized from hedged transactions within 12 months, approximate	1,400,000
Write off of deferred debt issuance cost	100,000
Write off of deferred debt remaining discount	100,000
Gain (loss) on extinguishment of debt	$ 8,400,000
Balance outstanding					$ 0	300,000,000
Senior Notes | 3.20% Senior Notes, due June 2023
Line of Credit Facility [Line Items]
Debt instrument face amount									$ 100,000,000
Stated interest rate					3.20%				3.20%
Balance outstanding					$ 100,000,000	100,000,000
Senior Notes | 3.37% Senior Notes, due June 2025
Line of Credit Facility [Line Items]
Debt instrument face amount									$ 100,000,000
Stated interest rate					3.37%				3.37%
Balance outstanding					$ 100,000,000	100,000,000
Senior Notes | 4.20% Senior Notes, due December 2021
Line of Credit Facility [Line Items]
Stated interest rate					4.20%
Balance outstanding					$ 350,000,000	$ 350,000,000
Letters of Credit | Line of Credit
Line of Credit Facility [Line Items]
Current borrowing capacity			$ 75,000,000
Swing line Loans | Line of Credit
Line of Credit Facility [Line Items]
Current borrowing capacity			$ 50,000,000