Employee Benefit Plans - Pension Plan Asset Allocations (Detail)	Dec. 31, 2014		Dec. 31, 2013
Defined Contribution Benefit Plans [Line Items]
Plan Assets	100.00%	[1]	100.00%	[1]
Equity securities
Defined Contribution Benefit Plans [Line Items]
Plan Assets	76.00%		78.00%
Cash and equivalents
Defined Contribution Benefit Plans [Line Items]
Plan Assets	4.00%		4.00%
Debt securities
Defined Contribution Benefit Plans [Line Items]
Plan Assets	20.00%		18.00%

[1] Our overall investment strategy is to achieve an asset allocation within the following ranges to achieve an appropriate rate of return relative to risk