Retirement and Benefit Plans (Plan Assumptions) (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
For measuring benefit obligations at year end
Discount rate	3.97%	4.16%	3.82%
Expected return on plan assets	7.00%	7.00%	7.25%
For measuring net periodic benefit cost
Discount rate	4.16%	3.82%	4.72%
Expected return on plan assets	7.00%	7.00%	7.25%