Loan Servicing, Mortgage Origination, and Loans Held for Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Characteristics and sensitivity analysis of the MSR
Residential Mortgages Serviced for Others Percentage				100.00%	100.00%
Weighted average life	7 years 18 days	6 years 3 months 18 days
Constant prepayment rate (as a percent)	9.60%	11.40%
Weighted average discount rate (as a percent)	9.80%	9.70%
Effect on fair value due to change in interest rates:
Custodial escrow balances maintained in connection with the loan servicing				$ 10,700	$ 10,100
MSRs
Changes in the fair value of MSRs and its offsetting hedge
Increase (decrease) in fair value of MSRs	$ 1,015	$ (1,618)	$ 1,058
Decay of MSRs	(3,371)	(2,381)	(886)
Gains (losses) related to derivatives	751	3,872	(681)
Net effect on Statements of Income	(1,605)	(127)	$ (509)
Effect on fair value due to change in interest rates:
25 basis point increase				1,562	1,365
50 basis point increase				2,950	2,555
25 basis point decrease				(1,866)	(1,562)
50 basis point decrease				$ (4,021)	$ (3,221)
Fixed-rate mortgage loans
Characteristics and sensitivity analysis of the MSR
Residential Mortgages Serviced for Others Percentage				99.40%	99.20%
Adjustable-rate mortgage loans
Characteristics and sensitivity analysis of the MSR
Residential Mortgages Serviced for Others Percentage				0.60%	0.80%
First Financial Holdings, Inc. ("First Financial")
Loans held for sale, loan servicing and mortgage origination
Residential mortgages serviced for others				$ 2,600,000	$ 2,300,000
Contractually specified servicing fees earned	6,300	5,400
First Financial Holdings, Inc. ("First Financial") | MSRs
Loans held for sale, loan servicing and mortgage origination
Mortgage servicing rights	21,600	21,600		$ 26,200	$ 21,600
Analysis of the activity in the MSRs
Balance at beginning of the period	21,600
Balance at end of period	$ 26,200	$ 21,600