Equity Incentive Plan - Valuation Assumptions (Details) - shares				12 Months Ended
	Nov. 01, 2017	Sep. 19, 2017	Aug. 01, 2017	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)				0	0
2008 Equity Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)	40,000,000	12,500,000	45,744,000
Risk-free rate of return	2.06%	1.89%	1.86%
Volatility (percent)	29.22%	30.06%	29.46%
Dividend yield (percent)	2.37%	1.98%	1.91%
Expected life	5 years 9 months	5 years 9 months	5 years 9 months