Derivative Instruments and Hedging Activities - Amounts included in accumulated other comprehensive income for derivatives designated as hedging instruments (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net [Line Items]
Accumulated other comprehensive (loss) income, fair value, net of taxes		$ (1,241)
Interest rate swap [Member] | Cash flow hedge [Member]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net [Line Items]
Accumulated other comprehensive (loss) income, fair value, net of taxes		$ (1,241)