Consolidated Statements Of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Regular dividends per share paid	$ 1.00	$ 1.00	$ 1.00
Extra dividends per share paid	$ 5.00	$ 5.00	$ 4.50