CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
NET INCOME / (LOSS) INCLUDING NCI		$ 874,536	$ 270,436	$ (1,144,182)	$ 916,292
OCI, NET OF TAX
Net unrealized changes in cash flow hedge derivative financial instruments, net of tax	[1]	(38,702)	8,217	116,951	16,354
Net unrealized (losses) / gains on AFS investment securities, net of tax		(41,551)	34,601	149,569	239,395
Pension and post-retirement actuarial gains, net of tax		18,240	542	19,360	12,744
TOTAL OTHER COMPREHENSIVE (LOSS) / GAIN, NET OF TAX		(62,013)	43,360	285,880	268,493
COMPREHENSIVE INCOME / (LOSS)		812,523	313,796	(858,302)	1,184,785
NET INCOME ATTRIBUTABLE TO NCI		101,701	66,831	82,087	250,086
COMPREHENSIVE INCOME / (LOSS) ATTRIBUTABLE TO SHUSA		$ 710,822	$ 246,965	$ (940,389)	$ 934,699

[1] Excludes $1.4 million and $(8.7) million of Other comprehensive income/(loss) attributable to NCI for the three-month and nine-month periods ended September 30, 2020, respectively, compared to $(3.2) million and $(19.7) million for the corresponding periods in 2019, respectively.