Consolidated Statements Of Stockholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Regular dividends per share (in dollars per share)	$ 1.00	$ 1.00	$ 1.00
Extra dividends per share (in dollars per share)	$ 5.00	$ 5.00	$ 5.00