Derivatives - Summary of Impact of Derivatives in Cash Flow Hedging Relationships on Statement of Operations and Statement of OCI (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative [Line Items]
Amortization Reclassified from OCI into Income (Loss)	$ (585)	$ (540)
Interest Expense [Member]
Derivative [Line Items]
Amortization Reclassified from OCI into Income (Loss)	$ (585)	$ (540)