Summary of Significant Accounting Policies Tax Characteristics of Dividends (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Characterization of Dividends Paid [Line Items]
Income Taxes Paid, Net	$ 7.8	$ 3.7	$ 21.0
Common Stock [Member]
Tax Characterization of Dividends Paid [Line Items]
Percent of Total Dividends Paid	100.00%	100.00%	100.00%
Ordinary Income [Member] | Common Stock [Member]
Tax Characterization of Dividends Paid [Line Items]
Percent of Total Dividends Paid	80.70%	78.40%	23.70%
Capital Gains [Member] | Common Stock [Member]
Tax Characterization of Dividends Paid [Line Items]
Percent of Total Dividends Paid	19.30%	21.60%	76.30%