Retirement Plans - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Percentage of compensation saved by participant for which employer contributes hundred percent	100.00%
Employer matching contribution for first one percent of compensation saved	1.00%
Percentage of compensation saved by participant for which employer contributes fifty percent	50.00%
Employer matching contribution for next five percent of compensation saved	5.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Time period completed by employee to cover under defined benefit pension plan	1 year
Minimum number of hours worked by employee to cover under defined benefit pension plan	1000 hours
Minimum age of employee to cover under defined benefit pension plan	21
Hancock Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of savings for calculating each employee participation in plan	50.00%
Maximum percentage of compensation on base percentage for participating in plan	6.00%
Whitney Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of savings for calculating each employee participation in plan	100.00%
Maximum percentage of compensation on base percentage for participating in plan	4.00%