Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 612,017	$ 659,749	$ 1,201,472	$ 1,342,838
Provision for credit losses	539,459	155,018	896,450	337,310
Noninterest income	272,354	284,281	606,596	542,041
Noninterest expense	579,450	598,314	3,388,510	1,180,287
Net (loss) income before income tax expense	(234,538)	190,698	(2,476,892)	367,282
Income tax (benefit) expense	(110,101)	30,512	(115,170)	66,115
Net (loss) income	(124,437)	160,186	(2,361,722)	301,167
Less: net income attributable to noncontrolling interests	472	599	973	1,155
Net (loss) income attributable to BBVA USA Bancshares, Inc.	(124,909)	159,587	(2,362,695)	300,012
Average assets	104,204,062	93,452,839	100,280,087	93,220,648
Operating Segments | Commercial Banking and Wealth
Segment Reporting Information [Line Items]
Net interest income (expense)	223,884	292,655	490,722	607,990
Provision for credit losses	170,749	78,678	212,933	136,117
Noninterest income	59,137	63,148	127,672	120,522
Noninterest expense	175,329	158,652	349,430	326,115
Net (loss) income before income tax expense	(63,057)	118,473	56,031	266,280
Income tax (benefit) expense	(13,242)	24,879	11,545	55,919
Net (loss) income	(49,815)	93,594	44,486	210,361
Less: net income attributable to noncontrolling interests	(55)	166	61	262
Net (loss) income attributable to BBVA USA Bancshares, Inc.	(49,760)	93,428	44,425	210,099
Average assets	44,982,771	39,950,464	43,080,319	40,170,674
Operating Segments | Retail Banking
Segment Reporting Information [Line Items]
Net interest income (expense)	230,551	326,298	525,560	675,674
Provision for credit losses	178,355	56,272	245,084	159,676
Noninterest income	114,247	121,905	244,951	233,823
Noninterest expense	296,430	306,413	601,687	604,336
Net (loss) income before income tax expense	(129,987)	85,518	(76,260)	145,485
Income tax (benefit) expense	(27,297)	17,959	(15,803)	30,552
Net (loss) income	(102,690)	67,559	(60,457)	114,933
Less: net income attributable to noncontrolling interests	0	0	0	0
Net (loss) income attributable to BBVA USA Bancshares, Inc.	(102,690)	67,559	(60,457)	114,933
Average assets	18,588,273	18,866,251	18,642,753	18,899,297
Operating Segments | Corporate and Investment Banking
Segment Reporting Information [Line Items]
Net interest income (expense)	25,412	32,430	56,191	66,248
Provision for credit losses	14,457	(675)	107,428	25,255
Noninterest income	70,177	39,711	110,312	76,228
Noninterest expense	40,436	39,183	101,831	79,062
Net (loss) income before income tax expense	40,696	33,633	(42,756)	38,159
Income tax (benefit) expense	8,546	7,063	(8,979)	8,013
Net (loss) income	32,150	26,570	(33,777)	30,146
Less: net income attributable to noncontrolling interests	0	0	0	0
Net (loss) income attributable to BBVA USA Bancshares, Inc.	32,150	26,570	(33,777)	30,146
Average assets	10,420,105	7,245,328	9,351,070	7,727,096
Operating Segments | Treasury
Segment Reporting Information [Line Items]
Net interest income (expense)	40,411	(18,782)	3,984	(38,806)
Provision for credit losses	1,958	(1,012)	1,721	(638)
Noninterest income	6,191	2,659	32,392	15,145
Noninterest expense	5,655	4,416	9,701	10,004
Net (loss) income before income tax expense	38,989	(19,527)	24,954	(33,027)
Income tax (benefit) expense	8,187	(4,101)	5,240	(6,936)
Net (loss) income	30,802	(15,426)	19,714	(26,091)
Less: net income attributable to noncontrolling interests	394	402	789	807
Net (loss) income attributable to BBVA USA Bancshares, Inc.	30,408	(15,828)	18,925	(26,898)
Average assets	24,538,397	18,997,865	22,396,303	18,110,961
Corporate Support and Other
Segment Reporting Information [Line Items]
Net interest income (expense)	91,759	27,148	125,015	31,732
Provision for credit losses	173,940	21,755	329,284	16,900
Noninterest income	22,602	56,858	91,269	96,323
Noninterest expense	61,600	89,650	2,325,861	160,770
Net (loss) income before income tax expense	(121,179)	(27,399)	(2,438,861)	(49,615)
Income tax (benefit) expense	(86,295)	(15,288)	(107,173)	(21,433)
Net (loss) income	(34,884)	(12,111)	(2,331,688)	(28,182)
Less: net income attributable to noncontrolling interests	133	31	123	86
Net (loss) income attributable to BBVA USA Bancshares, Inc.	(35,017)	(12,142)	(2,331,811)	(28,268)
Average assets	$ 5,674,516	$ 8,392,931	$ 6,809,642	$ 8,312,620