FIRST CITIZENS BANCSHARES, INC. (PARENT COMPANY) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Assets
Other assets	$ 286,430	$ 258,524
Total assets	20,881,493	20,806,659
Liabilities and Shareholders' Equity
Short-term borrowings	615,222	546,597
Long-term obligations	687,599	809,949
Other liabilities	140,270	81,885
Stockholders' equity	1,861,128	1,732,962	1,559,115	1,443,375
Total liabilities and shareholders' equity	20,881,493	20,806,659
Income Statement [Abstract]
Interest expense	144,192	195,125	227,644
Net interest income (loss)	870,967	774,243	510,515
Income tax benefit	115,103	110,518	66,768
Net income	195,028	193,044	116,331
OPERATING ACTIVITIES
Net amortization of premiums and accretion of discounts	(237,218)	(139,607)	45,186
Gain on repayment of long-term obligations	(9,685)	0	0
Securities gains	288	(1,952)	511
Change in other assets	89,979	(6,810)	(50,636)
Change in other liabilities	(1,392)	21,455	(28,585)
INVESTING ACTIVITIES
Net change in short-term borrowings	(283,440)	(500,217)	(83,719)
Retirement of long-term obligations	(320,730)	(114,425)
Repurchase of common stock	(24,387)	0	0
Cash dividends paid	(12,499)	(12,521)	(12,522)
Net change in cash	130,623	(20,064)	(113,133)
Cash and due from banks at beginning of period	460,178	480,242	593,375
Cash and due from banks at end of period	590,801	460,178	480,242
Cash payments for
Interest	157,477	196,002	240,686
Income taxes	91,465	187,183	20,640
Parent [Member]
Assets
Cash	10,765	14,010
Investment securities	235,617	94,610
Investment in subsidiaries	2,031,229	1,935,692
Due from subsidiaries	120,836	267,299
Other assets	114,852	89,342
Total assets	2,513,299	2,400,953
Liabilities and Shareholders' Equity
Short-term borrowings	375,396	371,350
Long-term obligations	251,697	273,197
Other liabilities	25,078	23,444
Stockholders' equity	1,861,128	1,732,962
Total liabilities and shareholders' equity	2,513,299	2,400,953
Income Statement [Abstract]
Interest income	1,345	1,524	5,285
Interest expense	21,512	22,633	22,786
Net interest income (loss)	(20,167)	(21,109)	(17,501)
Dividends from subsidiaries	82,812	50,424	60,509
Other income (loss)	9,699	(314)	(1,024)
Other operating expense	5,298	2,343	3,430
Income before income tax benefit and equity in undistributed net income of subsidiaries	67,046	26,658	38,554
Income tax benefit	(5,531)	(8,343)	(7,741)
Income before equity in undistributed net income of subsidiaries	72,577	35,001	46,295
Equity in undistributed net income of subsidiaries	122,451	158,043	70,036
Net income	195,028	193,044	116,331
OPERATING ACTIVITIES
Undistributed net income of subsidiaries	(122,451)	(158,043)	(70,036)
Net amortization of premiums and accretion of discounts	203	(113)	(246)
Gain on repayment of long-term obligations	(9,685)	0	0
Securities gains	(36)	377	615
Change in other assets	(20,951)	(30,443)	(1,924)
Change in other liabilities	(1,925)	1,409	(1,198)
Net cash provided by (Used in) Operating Activities	40,183	6,231	43,542
INVESTING ACTIVITIES
Net change in due from subsidiaries	146,463	59,249	(99,348)
Purchases of investment securities	(220,387)	(75,180)	0
Maturities and sales of investment securities	75,151	65,991	184,010
Investment in subsidiaries	0	(14,000)	(40,500)
Net Cash Provided by (Used in) Investing Activities	1,227	36,060	44,162
Net change in short-term borrowings	4,046	(24,227)	(76,995)
Retirement of long-term obligations	(11,815)	0	0
Repurchase of common stock	(24,387)	0	0
Cash dividends paid	(12,499)	(12,521)	(12,522)
Net cash used by financing activities	(44,655)	(36,748)	(89,517)
Net change in cash	(3,245)	5,543	(1,813)
Cash and due from banks at beginning of period	14,010	8,467	10,280
Cash and due from banks at end of period	10,765	14,010	8,467
Cash payments for
Interest	20,677	22,003	22,155
Income taxes	$ 91,465	$ 187,183	$ 20,640