Statements of Change in Common Stock Equity Parenthetical - $ / shares	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Common stock, dividends declared, per share	$ 0.385	$ 0.385	$ 0.360	$ 0.360	$ 0.360	$ 0.335	$ 1.130	$ 1.055	$ 1.49	$ 1.39