Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	$ 4,738	$ 4,229
AOCI activity before reclassifications	(318)	(44)
Amounts reclassified from AOCI	3	(2)
Net current period AOCI	(315)	(46)
Ending balance, shareholders' equity	10,570	4,321
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	10	12
Net current period AOCI	(315)	(46)
Ending balance, shareholders' equity	(305)	(34)
Unrealized (losses) gains on securities available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(9)	79
AOCI activity before reclassifications	(318)	(44)
Amounts reclassified from AOCI	0	(7)
Net current period AOCI	(318)	(51)
Ending balance, shareholders' equity	(327)	28
Unrealized (losses) gains on securities available for sale transferred to held to maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(7)	4
AOCI activity before reclassifications	0	0
Amounts reclassified from AOCI	1	0
Net current period AOCI	1	0
Ending balance, shareholders' equity	(6)	4
Defined benefit pension items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	26	(71)
AOCI activity before reclassifications	0	0
Amounts reclassified from AOCI	2	5
Net current period AOCI	2	5
Ending balance, shareholders' equity	$ 28	$ (66)