Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 22,900,000	$ 20,800,000
Criteria of employer to contribute in employee saving plan	100% of an employee's first 3% of contributions and 50% of their next 2% of contributions
Upper limit of employer match	4.00%
Maximum statutory compensation under code	255,000
Percentage contributions under the Savings Plan, vested	100.00%
Contributions and plan administration costs for savings plan	4,500,000	4,600,000	4,300,000
Maximum percentage of cash compensation allowed to be deferred under the deferred compensation plan	25.00%
Criteria for benefit distribution	Six months after termination of employment in a single lump sum payment or annual installments paid over a three or ten year term.
Deferred compensation adjustments due to fair value of the trust assets	2,800,000	900,000	(200,000)
Maximum number of years medical, dental and prescription drug coverage to spouse of deceased officer	30 years
Total liability recorded to provide medical, dental and prescription drug coverage	200,000	200,000
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization from accumulated other comprehensive income	$ 0
First Contributions [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer match to employee's contribution	100.00%
Second Contributions [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer match to employee's contribution	50.00%
Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target allocation ranges by asset class	75.00%
Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target allocation ranges by asset class	25.00%