Regulation and Capital Adequacy - Capital Ratios (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage ratio	9.30%	9.30%
Standardized Capital Rules [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1	$ 71,697	$ 71,363	$ 69,830
Tier 1 capital	81,744	81,511	78,433
Allowance for losses on loans and lending commitments	699	602
Other adjustments	(4)	(19)
Tier 2 capital	16,295	16,705	12,861
Total capital	98,039	98,216
Risk-weighted assets	$ 513,020	$ 524,107	619,216
CET1 ratio	14.00%	13.60%
Tier 1 capital ratio	15.90%	15.60%
Total capital ratio	19.10%	18.70%
Basel III Advanced Transitional [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1	$ 71,697	$ 71,363	69,830
Tier 1 capital	81,744	81,511	78,433
Standardized Tier 2 capital	16,295	16,705
Allowance for losses on loans and lending commitments	(699)	(602)
Tier 2 capital	15,596	16,103	12,545
Total capital	97,340	97,614
Risk-weighted assets	$ 579,996	$ 577,651	$ 570,313
CET1 ratio	12.40%	12.40%
Tier 1 capital ratio	14.10%	14.10%
Total capital ratio	16.80%	16.90%
GS Bank USA [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage ratio	15.00%	16.40%
GS Bank USA [Member] | Standardized Capital Rules [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1	$ 24,121	$ 23,017
Tier 1 capital	24,121	23,017
Tier 2 capital	2,381	2,311
Total capital	26,502	25,328
Risk-weighted assets	$ 194,629	$ 202,197
CET1 ratio	12.40%	11.40%
Tier 1 capital ratio	12.40%	11.40%
Total capital ratio	13.60%	12.50%
GS Bank USA [Member] | Basel III Advanced Transitional [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1	$ 24,121	$ 23,017
Tier 1 capital	24,121	23,017
Standardized Tier 2 capital	2,381	2,311
Allowance for losses on loans and lending commitments	(381)	(311)
Other adjustments	0	0
Tier 2 capital	2,000	2,000
Total capital	26,121	25,017
Risk-weighted assets	$ 137,135	$ 131,059
CET1 ratio	17.60%	17.60%
Tier 1 capital ratio	17.60%	17.60%
Total capital ratio	19.00%	19.10%