Retirement Plans - Defined Benefit Plans - Reconciliation of Projected Benefit Obligation and Funded Status (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Change in Projected Benefit Obligation:      
Benefit obligation at beginning of fiscal year $ 78,701 $ 81,944  
Service cost 5,747 6,613 7,082
Interest cost 3,678 3,115 2,876
Actuarial (gain) loss 17,493 (10,472)  
Benefits paid (2,922) (2,499)  
Curtailment 465 0 900
Benefit obligation at end of fiscal year 103,162 78,701 81,944
Change in Plan Assets:      
Plan assets at fair value at beginning of fiscal year 53,470 51,528  
Actual net return on plan assets 4,065 4,052  
Employer contributions 7,965 389 10,700
Benefits paid (2,922) (2,499)  
Plan assets at fair value at end of fiscal year 62,578 53,470 51,528
Unfunded projected benefit obligation recognized in other liabilities on the consolidated balance sheets $ (40,584) $ (25,231)