Shareholders' Equity Cash Dividends (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Equity [Abstract]
Special dividend declared in December 2017 and paid in January 2018			$ 1.00
Special dividend declared in December 2020 and paid in January 2021	$ 1.00
Special Dividend, Per Share, Paid		$ 1.00