Retirement Plans - Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets for Qualified and Non-Qualified Pension Plans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 139,731	$ 153,958	$ 143,307
Accumulated benefit obligation	139,483	153,606
Fair value of plan assets	139,737	113,416	105,330
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	120,512	133,116
Accumulated benefit obligation	120,512	133,116
Fair value of plan assets	139,737	113,416
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	19,219	20,842
Accumulated benefit obligation	18,971	20,490
Fair value of plan assets