Targeted and Actual Weighted Average Asset Allocations by Plan Asset Category (Detail)		Dec. 31, 2015	Dec. 31, 2014
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		69.00%	62.00%
Total equity securities	[1]		64.00%
Bancorp common stock		2.00%	2.00%
Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations			20.00%
Alternative strategies
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations			12.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations			4.00%
Total
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		100.00%	100.00%
Targeted Range 60 to 90 Percent | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total equity securities	[1],[2]	71.00%
Targeted Range 5 to 25 Percent | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	[2]	16.00%
Targeted Range 3 to 11 Percent | Alternative strategies
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	[2]	7.00%
Targeted Range 0 to 13 Percent | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	[2]	6.00%

[1] Includes mutual and exchange-traded funds.

[2] These reflect the targeted ranges for the year ended December 31, 2015.