Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 641,850	$ 641,041	$ 1,843,322	$ 1,983,879
Allocated provision (credit) for credit losses	150,977	140,629	1,047,427	477,939
Noninterest income	284,660	321,319	891,256	863,360
Noninterest expense	595,628	598,887	3,984,138	1,779,174
Net income (loss) before income tax (benefit) expense	179,905	222,844	(2,296,987)	590,126
Income tax (benefit) expense	13,664	39,899	(101,506)	106,014
Net income (loss)	166,241	182,945	(2,195,481)	484,112
Less: net income attributable to noncontrolling interests	401	514	1,374	1,669
Net income (loss) attributable to BBVA USA Bancshares, Inc.	165,840	182,431	(2,196,855)	482,443
Average assets	104,282,898	94,942,456	101,058,770	93,800,891
Operating Segments | Commercial Banking and Wealth
Segment Reporting Information [Line Items]
Net interest income (expense)	243,434	267,905	734,156	875,894
Allocated provision (credit) for credit losses	53,546	33,653	266,479	169,770
Noninterest income	59,271	62,620	186,942	183,142
Noninterest expense	159,822	160,024	509,251	486,138
Net income (loss) before income tax (benefit) expense	89,337	136,848	145,368	403,128
Income tax (benefit) expense	18,761	28,738	30,527	84,657
Net income (loss)	70,576	108,110	114,841	318,471
Less: net income attributable to noncontrolling interests	40	87	101	349
Net income (loss) attributable to BBVA USA Bancshares, Inc.	70,536	108,023	114,740	318,122
Average assets	44,218,296	39,960,074	43,462,414	40,099,702
Operating Segments | Retail Banking
Segment Reporting Information [Line Items]
Net interest income (expense)	247,457	299,535	773,017	975,209
Allocated provision (credit) for credit losses	12,515	69,888	257,599	229,564
Noninterest income	118,358	126,270	363,309	360,094
Noninterest expense	309,173	308,468	910,861	912,804
Net income (loss) before income tax (benefit) expense	44,127	47,449	(32,134)	192,935
Income tax (benefit) expense	9,267	9,964	(6,748)	40,516
Net income (loss)	34,860	37,485	(25,386)	152,419
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to BBVA USA Bancshares, Inc.	34,860	37,485	(25,386)	152,419
Average assets	18,338,000	18,829,121	18,540,427	18,875,648
Operating Segments | Corporate and Investment Banking
Segment Reporting Information [Line Items]
Net interest income (expense)	29,515	24,800	85,706	91,048
Allocated provision (credit) for credit losses	7,157	13,955	114,585	39,210
Noninterest income	52,060	47,356	162,372	123,584
Noninterest expense	38,342	39,311	140,173	118,373
Net income (loss) before income tax (benefit) expense	36,076	18,890	(6,680)	57,049
Income tax (benefit) expense	7,576	3,967	(1,403)	11,980
Net income (loss)	28,500	14,923	(5,277)	45,069
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to BBVA USA Bancshares, Inc.	28,500	14,923	(5,277)	45,069
Average assets	8,102,696	7,855,727	8,366,581	7,770,444
Operating Segments | Treasury
Segment Reporting Information [Line Items]
Net interest income (expense)	64,107	(40,478)	68,091	(79,284)
Allocated provision (credit) for credit losses	(1,468)	491	253	(147)
Noninterest income	3,620	24,882	36,012	40,027
Noninterest expense	4,594	5,009	14,294	15,013
Net income (loss) before income tax (benefit) expense	64,601	(21,096)	89,556	(54,123)
Income tax (benefit) expense	13,566	(4,430)	18,807	(11,366)
Net income (loss)	51,035	(16,666)	70,749	(42,757)
Less: net income attributable to noncontrolling interests	391	400	1,181	1,207
Net income (loss) attributable to BBVA USA Bancshares, Inc.	50,644	(17,066)	69,568	(43,964)
Average assets	28,065,244	19,898,446	24,299,743	18,713,337
Corporate Support and Other
Segment Reporting Information [Line Items]
Net interest income (expense)	57,337	89,279	182,352	121,012
Allocated provision (credit) for credit losses	79,227	22,642	408,511	39,542
Noninterest income	51,351	60,191	142,621	156,513
Noninterest expense	83,697	86,075	2,409,559	246,846
Net income (loss) before income tax (benefit) expense	(54,236)	40,753	(2,493,097)	(8,863)
Income tax (benefit) expense	(35,506)	1,660	(142,689)	(19,773)
Net income (loss)	(18,730)	39,093	(2,350,408)	10,910
Less: net income attributable to noncontrolling interests	(30)	27	92	113
Net income (loss) attributable to BBVA USA Bancshares, Inc.	(18,700)	39,066	(2,350,500)	10,797
Average assets	$ 5,558,662	$ 8,399,088	$ 6,389,605	$ 8,341,760