First Financial Holdings, Inc. (Parent Company Only) Condensed Financial Information (Detail) - Schedule of Condensed Balance Sheet (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Sep. 30, 2009
Assets
Cash and cash equivalents	$ 117,451	$ 76,675	$ 85,937	$ 53,404	$ 55,274	$ 74,621
Securities available for sale, at fair value	253,798	404,550	412,108
Other assets	77,199	95,994	118,560
Total assets	3,215,558	3,146,964	3,206,310
Liabilities and Shareholders’ Equity
Shareholders’ equity	299,641	277,178	268,506		318,190	351,649
Total liabilities and shareholders’ equity	3,215,558	3,146,964	3,206,310
Parent [Member]
Assets
Cash and cash equivalents	18,095	39,015	43,931
Securities available for sale, at fair value	18	27	27
Investment in subsidiaries	327,335	281,456	270,341
Other assets	3,717	5,305	5,496
Total assets	349,165	325,803	319,795
Liabilities and Shareholders’ Equity
Accrued expenses	3,132	2,233	4,897
Long-term debt	46,392	46,392	46,392
Shareholders’ equity	299,641	277,178	268,506
Total liabilities and shareholders’ equity	$ 349,165	$ 325,803	$ 319,795