Summary of Significant Accounting Policies Organization and Nature of Operations (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) country $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Accounting Policies [Abstract]
Number of Countries in which Entity Operates | country	75
Years in operation	50 years
Common Stock, Shares Authorized | shares	1,356	1,356
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.001	$ 0.001
Restricted Cash, Current | $	$ 167	$ 182