Employer Sponsored Benefit Plan (Plan Assets and Benefit Obligations) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in benefit obligation:
Net benefit obligation at beginning of year	$ 53,427	$ 60,020
Interest cost	2,348	2,453	2,583
Actuarial loss (gain)	7,654	(6,900)
Gross benefits paid	(12,602)	(2,146)
Net benefit obligation at end of year	50,827	53,427	60,020
Change in plan assets:
Fair value of plan assets at beginning of year	40,680	36,355
Actual return on plan assets	945	5,226
Contributions	4,252	1,245
Gross benefits paid	(12,602)	(2,146)
Fair value of plan assets at end of year	33,275	40,680	36,355
Net benefit obligation in excess of plan assets	(17,552)	(12,747)
Balance sheet amounts:
Noncurrent liabilities	(17,552)	(12,747)
Total liabilities	(17,552)	(12,747)
Amounts recognized in accumulated other comprehensive income, net of tax consist of:
Net actuarial loss	17,228	14,830
Net amount recognized	$ 17,228	$ 14,830