Fair Values of our Derivative Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 232	[1]	$ 259	[1]
Derivative liabilities	562	[1]	105	[1]
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	232	[1]	259	[1]
Derivative liabilities	$ 562	[1]	$ 105	[1]

[1] Based on observable market transactions of spot and forward rates.