Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Common stock, cash dividends declared per share	$ 0.76	$ 0.76	$ 0.76	$ 0.76	$ 0.75	$ 0.75	$ 0.75	$ 0.75	$ 3.04	$ 3.00	$ 2.18