Supplemental Equity and Comprehensive Income Information - Dividends (Details) - $ / shares	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Dividends declared in period (in dollars per share)	$ 1.48	$ 1.48	$ 1.48	$ 1.47	$ 1.47	$ 1.47	$ 4.44	$ 4.41