Postretirement Benefit Plans - Defined Contribution Plan Expenses for the Company's Retirement Savings Plans and Profit Sharing Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans And Other Postretirement Benefit Plans [Line Items]
Total	$ 8,184	$ 9,304	$ 10,046
Retirement Savings Plans [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans [Line Items]
Total	4,565	4,500	4,284
Profit Sharing Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans [Line Items]
Total	$ 3,619	$ 4,804	$ 5,762