Operating Segment Information (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013 Banks	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 Banks	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	$ 0				$ (3,428,000)				$ 0	$ (3,428,000)
Net interest income	432,035,000	415,521,000	430,657,000	418,115,000	429,957,000	438,161,000	426,344,000	437,478,000	1,696,328,000	1,731,940,000	1,756,185,000
Provision for loan losses	(30,538,000)	(5,573,000)	(21,990,000)	(29,035,000)	(10,401,000)	(1,889,000)	10,853,000	15,664,000	(87,136,000)	14,227,000	74,532,000
Loans and Leases Receivable, Net of Deferred Income	39,043,365,000				37,665,247,000				39,043,365,000	37,665,247,000
Deposits	46,361,880,000				46,133,073,000				46,361,880,000	46,133,073,000
Carrying value, Preferred stock	1,003,970,000				1,128,302,000				1,003,970,000	1,128,302,000
Net interest income after provision for loan losses									1,783,464,000	1,717,713,000	1,681,653,000
Net impairment losses on investment securities	(141,733,000)	(9,067,000)	(4,217,000)	(10,117,000)	83,808,000	2,736,000	7,308,000	10,209,000	(165,134,000)	(104,061,000)	(33,683,000)
Other noninterest income									17,940,000	13,129,000	29,607,000
Noninterest expense	494,750,000	370,663,000	451,678,000	397,348,000	407,014,000	394,975,000	401,656,000	392,372,000	1,714,439,000	1,596,017,000	1,658,564,000
Income (loss) before income taxes	(63,327,000)	172,621,000	126,117,000	171,021,000	87,503,000	170,301,000	142,500,000	141,262,000	406,432,000	541,566,000	521,273,000
Income Tax Expense (Benefit)									142,977,000	193,416,000	198,583,000
Net income (loss)	(41,472,000)	111,514,000	83,026,000	110,387,000	57,686,000	109,597,000	91,464,000	89,403,000	263,455,000	348,150,000	322,690,000
Cash and due from banks	1,175,083,000				1,841,907,000				1,175,083,000	1,841,907,000	1,224,350,000	924,126,000
Assets	56,031,127,000				55,511,918,000				56,031,127,000	55,511,918,000
Number of community/regional banks operating in distinct geographical areas	8								8
Total shareholders' equity	6,464,563,000				6,048,641,000				6,464,563,000	6,048,641,000	6,983,228,000	6,647,214,000
Zions Bank [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									595,000,000	657,100,000	683,300,000
Provision for loan losses									(40,500,000)	88,300,000	128,300,000
Money Market Funds, at Carrying Value	3,888,000,000				2,855,000,000				3,888,000,000	2,855,000,000	2,198,000,000
Investment and Trading Securities	1,520,000,000				1,273,000,000				1,520,000,000	1,273,000,000	1,460,000,000
Loans and Leases Receivable, Net of Deferred Income	12,259,000,000				12,490,000,000				12,259,000,000	12,490,000,000	12,751,000,000
Deposits	16,257,000,000				15,575,000,000				16,257,000,000	15,575,000,000	14,905,000,000
Carrying value, Preferred stock	280,000,000				280,000,000				280,000,000	280,000,000	480,000,000
Average Common Equity	1,523,000,000				1,519,000,000				1,523,000,000	1,519,000,000	1,379,000,000
Net interest income after provision for loan losses									635,500,000	568,800,000	555,000,000
Net impairment losses on investment securities									7,700,000	3,200,000	300,000
Loss on sale of investment securities to Parent									0	0	0
Other noninterest income									199,900,000	221,400,000	219,200,000
Noninterest expense									481,400,000	493,100,000	547,400,000
Income (loss) before income taxes									346,300,000	293,900,000	226,500,000
Income Tax Expense (Benefit)									121,700,000	104,600,000	76,000,000
Net income (loss)									224,600,000	189,300,000	150,500,000
Cash and due from banks	363,000,000				650,000,000				363,000,000	650,000,000	416,000,000
Assets	18,590,000,000				17,930,000,000				18,590,000,000	17,930,000,000	17,531,000,000
Total shareholders' equity	1,803,000,000				1,799,000,000				1,803,000,000	1,799,000,000	1,859,000,000
CB&T [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									469,000,000	466,700,000	506,900,000
Provision for loan losses									(16,700,000)	(7,900,000)	(9,500,000)
Money Market Funds, at Carrying Value	1,108,000,000				1,449,000,000				1,108,000,000	1,449,000,000	1,090,000,000
Investment and Trading Securities	331,000,000				350,000,000				331,000,000	350,000,000	335,000,000
Loans and Leases Receivable, Net of Deferred Income	8,574,000,000				8,259,000,000				8,574,000,000	8,259,000,000	8,392,000,000
Deposits	9,327,000,000				9,483,000,000				9,327,000,000	9,483,000,000	9,192,000,000
Carrying value, Preferred stock	162,000,000				162,000,000				162,000,000	162,000,000	262,000,000
Average Common Equity	1,342,000,000				1,322,000,000				1,342,000,000	1,322,000,000	1,270,000,000
Net interest income after provision for loan losses									485,700,000	474,600,000	516,400,000
Net impairment losses on investment securities									0	0	500,000
Loss on sale of investment securities to Parent									0	(9,200,000)	(43,900,000)
Other noninterest income									79,300,000	75,300,000	105,400,000
Noninterest expense									352,400,000	330,200,000	355,000,000
Income (loss) before income taxes									212,600,000	210,500,000	222,400,000
Income Tax Expense (Benefit)									72,500,000	83,400,000	88,000,000
Net income (loss)									140,100,000	127,100,000	134,400,000
Cash and due from banks	157,000,000				205,000,000				157,000,000	205,000,000	175,000,000
Assets	10,923,000,000				11,069,000,000				10,923,000,000	11,069,000,000	10,894,000,000
Total shareholders' equity	1,504,000,000				1,484,000,000				1,504,000,000	1,484,000,000	1,532,000,000
Amegy [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									381,500,000	371,500,000	391,200,000
Provision for loan losses									4,200,000	(63,900,000)	(37,400,000)
Money Market Funds, at Carrying Value	2,551,000,000				2,308,000,000				2,551,000,000	2,308,000,000	2,222,000,000
Investment and Trading Securities	362,000,000				439,000,000				362,000,000	439,000,000	475,000,000
Loans and Leases Receivable, Net of Deferred Income	9,217,000,000				8,450,000,000				9,217,000,000	8,450,000,000	8,031,000,000
Deposits	11,198,000,000				10,706,000,000				11,198,000,000	10,706,000,000	9,731,000,000
Carrying value, Preferred stock	226,000,000				251,000,000				226,000,000	251,000,000	488,000,000
Average Common Equity	1,845,000,000				1,725,000,000				1,845,000,000	1,725,000,000	1,630,000,000
Net interest income after provision for loan losses									377,300,000	435,400,000	428,600,000
Net impairment losses on investment securities									0	0	0
Loss on sale of investment securities to Parent									0	0	0
Other noninterest income									146,400,000	156,100,000	138,400,000
Noninterest expense									333,400,000	340,200,000	324,900,000
Income (loss) before income taxes									190,300,000	251,300,000	242,100,000
Income Tax Expense (Benefit)									59,800,000	84,600,000	80,500,000
Net income (loss)									130,500,000	166,700,000	161,600,000
Cash and due from banks	437,000,000				754,000,000				437,000,000	754,000,000	406,000,000
Assets	13,705,000,000				13,119,000,000				13,705,000,000	13,119,000,000	12,282,000,000
Total shareholders' equity	2,071,000,000				1,976,000,000				2,071,000,000	1,976,000,000	2,118,000,000
NBA [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									163,000,000	167,700,000	172,100,000
Provision for loan losses									(15,000,000)	(600,000)	9,600,000
Money Market Funds, at Carrying Value	220,000,000				385,000,000				220,000,000	385,000,000	604,000,000
Investment and Trading Securities	362,000,000				263,000,000				362,000,000	263,000,000	271,000,000
Loans and Leases Receivable, Net of Deferred Income	3,724,000,000				3,604,000,000				3,724,000,000	3,604,000,000	3,304,000,000
Deposits	3,931,000,000				3,874,000,000				3,931,000,000	3,874,000,000	3,731,000,000
Carrying value, Preferred stock	120,000,000				180,000,000				120,000,000	180,000,000	305,000,000
Average Common Equity	418,000,000				399,000,000				418,000,000	399,000,000	350,000,000
Net interest income after provision for loan losses									178,000,000	168,300,000	162,500,000
Net impairment losses on investment securities									0	0	0
Loss on sale of investment securities to Parent									0	0	0
Other noninterest income									35,000,000	32,100,000	34,400,000
Noninterest expense									142,700,000	152,500,000	154,700,000
Income (loss) before income taxes									70,300,000	47,900,000	42,200,000
Income Tax Expense (Benefit)									26,400,000	17,000,000	16,700,000
Net income (loss)									43,900,000	30,900,000	25,500,000
Cash and due from banks	77,000,000				86,000,000				77,000,000	86,000,000	71,000,000
Assets	4,579,000,000				4,575,000,000				4,579,000,000	4,575,000,000	4,485,000,000
Total shareholders' equity	538,000,000				579,000,000				538,000,000	579,000,000	655,000,000
NSB [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									113,600,000	123,400,000	135,000,000
Provision for loan losses									(12,000,000)	(9,600,000)	(38,300,000)
Money Market Funds, at Carrying Value	710,000,000				1,031,000,000				710,000,000	1,031,000,000	905,000,000
Investment and Trading Securities	774,000,000				742,000,000				774,000,000	742,000,000	748,000,000
Loans and Leases Receivable, Net of Deferred Income	2,297,000,000				2,100,000,000				2,297,000,000	2,100,000,000	2,235,000,000
Deposits	3,590,000,000				3,604,000,000				3,590,000,000	3,604,000,000	3,546,000,000
Carrying value, Preferred stock	50,000,000				140,000,000				50,000,000	140,000,000	260,000,000
Average Common Equity	317,000,000				298,000,000				317,000,000	298,000,000	273,000,000
Net interest income after provision for loan losses									125,600,000	133,000,000	173,300,000
Net impairment losses on investment securities									3,300,000	0	0
Loss on sale of investment securities to Parent									0	0	0
Other noninterest income									37,800,000	33,700,000	37,400,000
Noninterest expense									131,800,000	133,600,000	139,300,000
Income (loss) before income taxes									28,300,000	33,100,000	71,400,000
Income Tax Expense (Benefit)									9,500,000	11,300,000	24,800,000
Net income (loss)									18,800,000	21,800,000	46,600,000
Cash and due from banks	79,000,000				59,000,000				79,000,000	59,000,000	73,000,000
Assets	3,980,000,000				4,061,000,000				3,980,000,000	4,061,000,000	4,100,000,000
Total shareholders' equity	367,000,000				438,000,000				367,000,000	438,000,000	533,000,000
Vectra [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									102,700,000	108,700,000	104,300,000
Provision for loan losses									(4,900,000)	7,000,000	14,000,000
Money Market Funds, at Carrying Value	6,000,000				31,000,000				6,000,000	31,000,000	52,000,000
Investment and Trading Securities	166,000,000				187,000,000				166,000,000	187,000,000	227,000,000
Loans and Leases Receivable, Net of Deferred Income	2,278,000,000				2,128,000,000				2,278,000,000	2,128,000,000	1,914,000,000
Deposits	2,178,000,000				2,164,000,000				2,178,000,000	2,164,000,000	2,004,000,000
Carrying value, Preferred stock	70,000,000				70,000,000				70,000,000	70,000,000	70,000,000
Average Common Equity	246,000,000				224,000,000				246,000,000	224,000,000	200,000,000
Net interest income after provision for loan losses									107,600,000	101,700,000	90,300,000
Net impairment losses on investment securities									100,000	600,000	800,000
Loss on sale of investment securities to Parent									0	0	(28,900,000)
Other noninterest income									24,600,000	25,300,000	21,700,000
Noninterest expense									99,500,000	98,300,000	100,700,000
Income (loss) before income taxes									32,600,000	28,100,000	(18,400,000)
Income Tax Expense (Benefit)									11,200,000	9,200,000	(8,300,000)
Net income (loss)									21,400,000	18,900,000	(10,100,000)
Cash and due from banks	51,000,000				58,000,000				51,000,000	58,000,000	55,000,000
Assets	2,571,000,000				2,511,000,000				2,571,000,000	2,511,000,000	2,341,000,000
Total shareholders' equity	316,000,000				294,000,000				316,000,000	294,000,000	270,000,000
TCBW [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				0				0	0	0
Net interest income									27,300,000	27,400,000	29,600,000
Provision for loan losses									(1,800,000)	400,000	7,800,000
Money Market Funds, at Carrying Value	181,000,000				251,000,000				181,000,000	251,000,000	143,000,000
Investment and Trading Securities	91,000,000				104,000,000				91,000,000	104,000,000	126,000,000
Loans and Leases Receivable, Net of Deferred Income	630,000,000				571,000,000				630,000,000	571,000,000	562,000,000
Deposits	793,000,000				791,000,000				793,000,000	791,000,000	693,000,000
Carrying value, Preferred stock	3,000,000				3,000,000				3,000,000	3,000,000	15,000,000
Average Common Equity	87,000,000				82,000,000				87,000,000	82,000,000	75,000,000
Net interest income after provision for loan losses									29,100,000	27,000,000	21,800,000
Net impairment losses on investment securities									0	0	0
Loss on sale of investment securities to Parent									(2,700,000)	0	(4,800,000)
Other noninterest income									4,100,000	3,800,000	3,500,000
Noninterest expense									18,800,000	18,900,000	16,700,000
Income (loss) before income taxes									11,700,000	11,900,000	3,800,000
Income Tax Expense (Benefit)									4,000,000	4,000,000	1,100,000
Net income (loss)									7,700,000	7,900,000	2,700,000
Cash and due from banks	28,000,000				22,000,000				28,000,000	22,000,000	28,000,000
Assets	943,000,000				961,000,000				943,000,000	961,000,000	874,000,000
Total shareholders' equity	90,000,000				85,000,000				90,000,000	85,000,000	90,000,000
Other Banks [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				(3,000,000)				0	(3,000,000)	(2,000,000)
Net interest income									(155,800,000)	(190,600,000)	(266,200,000)
Provision for loan losses									(400,000)	500,000	0
Money Market Funds, at Carrying Value	(207,000,000)				444,000,000				(207,000,000)	444,000,000	(91,000,000)
Investment and Trading Securities	719,000,000				519,000,000				719,000,000	519,000,000	437,000,000
Loans and Leases Receivable, Net of Deferred Income	64,000,000				63,000,000				64,000,000	63,000,000	69,000,000
Deposits	(912,000,000)				(64,000,000)				(912,000,000)	(64,000,000)	(926,000,000)
Carrying value, Preferred stock	93,000,000				42,000,000				93,000,000	42,000,000	497,000,000
Average Common Equity	(317,000,000)				(645,000,000)				(317,000,000)	(645,000,000)	(569,000,000)
Net interest income after provision for loan losses									(155,400,000)	(191,100,000)	(266,200,000)
Net impairment losses on investment securities									154,000,000	100,300,000	32,100,000
Loss on sale of investment securities to Parent									2,700,000	9,200,000	77,600,000
Other noninterest income									(24,600,000)	(23,700,000)	(28,100,000)
Noninterest expense									154,400,000	29,200,000	19,900,000
Income (loss) before income taxes									(485,700,000)	(335,100,000)	(268,700,000)
Income Tax Expense (Benefit)									(162,200,000)	(120,700,000)	(80,200,000)
Net income (loss)									(323,500,000)	(214,400,000)	(188,500,000)
Cash and due from banks	(17,000,000)				8,000,000				(17,000,000)	8,000,000	0
Assets	740,000,000				1,286,000,000				740,000,000	1,286,000,000	642,000,000
Total shareholders' equity	(224,000,000)				(606,000,000)				(224,000,000)	(606,000,000)	(74,000,000)
Consolidated Company [Member]
Segment Reporting Information [Line Items]
Stockholders' Equity Attributable to Noncontrolling Interest	0				(3,000,000)				0	(3,000,000)	(2,000,000)
Net interest income									1,696,300,000	1,731,900,000	1,756,200,000
Provision for loan losses									(87,100,000)	14,200,000	74,500,000
Money Market Funds, at Carrying Value	8,457,000,000				8,754,000,000				8,457,000,000	8,754,000,000	7,123,000,000
Investment and Trading Securities	4,325,000,000				3,877,000,000				4,325,000,000	3,877,000,000	4,079,000,000
Loans and Leases Receivable, Net of Deferred Income	39,043,000,000				37,665,000,000				39,043,000,000	37,665,000,000	37,258,000,000
Deposits	46,362,000,000				46,133,000,000				46,362,000,000	46,133,000,000	42,876,000,000
Carrying value, Preferred stock	1,004,000,000				1,128,000,000				1,004,000,000	1,128,000,000	2,377,000,000
Average Common Equity	5,461,000,000				4,924,000,000				5,461,000,000	4,924,000,000	4,608,000,000
Net interest income after provision for loan losses									1,783,400,000	1,717,700,000	1,681,700,000
Net impairment losses on investment securities									165,100,000	104,100,000	33,700,000
Loss on sale of investment securities to Parent									0	0	0
Other noninterest income									502,500,000	524,000,000	531,900,000
Noninterest expense									1,714,400,000	1,596,000,000	1,658,600,000
Income (loss) before income taxes									406,400,000	541,600,000	521,300,000
Income Tax Expense (Benefit)									142,900,000	193,400,000	198,600,000
Net income (loss)									263,500,000	348,200,000	322,700,000
Cash and due from banks	1,175,000,000				1,842,000,000				1,175,000,000	1,842,000,000	1,224,000,000
Assets	56,031,000,000				55,512,000,000				56,031,000,000	55,512,000,000	53,149,000,000
Total shareholders' equity	$ 6,465,000,000				$ 6,049,000,000				$ 6,465,000,000	$ 6,049,000,000	$ 6,983,000,000