Employee Benefit Plans (Asset Allocation) (Detail)	Dec. 31, 2012	Dec. 31, 2011
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	33.70%	61.40%
Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	40.30%	36.40%
Balance Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	25.40%
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	0.60%	2.20%