Consolidated Statements of Cash Flows Supplemental Noncash Investing Activities - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Noncash or Part Noncash Acquisition, Investments Acquired	$ 9,100,000	$ 16,800,000	$ 2,500,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	12,000,000.0
NoncashOrPartNoncashAcquisitionUnsettledSecurities	5,300,000	$ 0	$ 0
Property, Plant and Equipment
Noncash or Part Noncash Acquisitions [Line Items]
Accrued Liabilities	$ 800,000