Accounting Changes Adjustments for New Accounting Pronouncements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 411,700,000	$ 335,900,000	$ 460,700,000
Operating Lease, Liability	429,400,000	348,600,000	483,600,000
Shareholders’ equity	1,835,100,000	$ 1,957,400,000		$ 1,788,100,000
Reclassification out of Accumulated Other Comprehensive Income [Domain] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shareholders’ equity	0			$ 0	$ (19,400,000)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Tax Assets, Deferred Gain on Sale Leaseback Transaction	$ 4,000,000.0
Accounting Standards Update 2016-02 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shareholders’ equity			$ 39,400,000