Short-Term Borrowings and Long-Term Debt - Interest Expense and Senior Notes (Details) - USD ($)		1 Months Ended	12 Months Ended
	Jun. 05, 2020	Jan. 31, 2015	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Interest expense on debt			$ 25,100,000	$ 35,100,000	$ 46,600,000
Weighted average interest rate on short-term borrowings			80.00%	1.55%
Debt Instrument [Line Items]
Long-term debt			$ 843,628,000	$ 347,987,000
Proceeds from issuance of long-term debt			$ 495,024,000	$ 0	$ 0
Weighted average interest rate on short-term borrowings			80.00%	1.55%
Senior Notes | 3.50% Senior Notes
Debt Instrument [Line Items]
Principal value		$ 350,000,000	$ 350,000,000
Stated interest rate			3.50%
Proceeds from issuance of senior notes, net of discount and issuance cost		$ 346,400,000
Long-term debt			$ 348,348,000	$ 347,987,000
Debt issuance costs			1,600,000
Discount on debt			100,000
Senior Notes | 3.125% Senior Notes
Debt Instrument [Line Items]
Principal value	$ 500,000,000.0		$ 500,000,000
Stated interest rate			3.125%
Proceeds from issuance of senior notes, net of discount and issuance cost	495,400,000
Long-term debt			$ 495,280,000	$ 0
Debt issuance costs			$ 4,300,000
Discount on debt	$ 400,000