Investments - Unrealized Capital Losses 1 (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Available For Sale Securities Change in Loss Position	$ 563
Fair value decline below amortized cost greater than 20%
Available-for-sale Securities Including Securities Pledged [Line Items]
More Than Twelve Months Below Amortized Cost, Unrealized Capital Loss	$ 4
More than twelve months below amortized cost, Number of Securities | securities	4