Employee Benefit Plans (Principal Components of Employee Benefit Plan Expenses) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Expense
Employee benefit plan expenses	$ 77,122	$ 53,671	$ 63,585
Other Plans, Net
Expense
Employee benefit plan expenses	3,812	9,259	15,479
Savings Plan
Expense
Employee benefit plan expenses	37,326	16,333	10,458
Defined Benefit Pension Plans
Expense
Employee benefit plan expenses	18,611	13,465	20,975
Unfunded Supplemental Benefit Plans
Expense
Employee benefit plan expenses	$ 17,373	$ 14,614	$ 16,673