Derivative Instruments and Hedging Activities - Income for derivatives designated as hedging instruments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Net loss	$ (1,857)	$ 110	$ (1,742)	$ 218
Interest expense [Member] | Interest rate swap [Member] | Cash flow hedge [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swap-cash flow hedge-loss on termination	(1,866)		(1,866)
Interest rate swap-cash flow hedge-interest payments	9	110	124	218
Interest rate swap-cash flow hedge-ineffectiveness