Derivative Financial Instruments - Interest Rate Derivatives Designated and Non Designated (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 [Line Items]
Unrealized Gain on Hedge in Other Comprehensive Income	$ 131	$ (25)	$ 130	$ (57)
Cash Flow Hedging [Member] | Interest Rate Caps [Member] | 0.5% Strike Rate Derivatives [Member]
Derivative [Line Items]
Derivative Maturity Period			Aug 2014
Strike Rate	0.50%		0.50%
Notional Amount of Hedge	13,337		13,337
Cost of Hedge			22
Estimated Fair Value			(1)
Unrealized Gain on Hedge in Other Comprehensive Income
Valuations Included in Other Comprehensive Income for the Six Months Ended June 30, 2013
Cash Flow Hedging [Member] | Interest Rate Cap One Member | 0.5% Strike Rate Derivatives [Member]
Derivative [Line Items]
Derivative Maturity Period			May 2016
Strike Rate	0.50%		0.50%
Notional Amount of Hedge	42,922		42,922
Cost of Hedge
Estimated Fair Value			132
Unrealized Gain on Hedge in Other Comprehensive Income			132
Valuations Included in Other Comprehensive Income for the Six Months Ended June 30, 2013			132
Not Designated as Hedging Instrument [Member] | Interest Rate Caps [Member] | 1.25% Strike Rate Derivatives [Member]
Derivative [Line Items]
Derivative Maturity Period			May 2013
Strike Rate	1.25%		1.25%
Notional Amount of Hedge	51,982		51,982
Cost of Hedge			196
Estimated Fair Value
Change in Cap Valuations Included in Interest Expense
Not Designated as Hedging Instrument [Member] | Interest Rate Caps [Member] | 1.75% Strike Rate Derivatives [Member]
Derivative [Line Items]
Derivative Maturity Period			May 2014
Strike Rate	1.75%		1.75%
Notional Amount of Hedge	51,982		51,982
Cost of Hedge			434
Estimated Fair Value
Change in Cap Valuations Included in Interest Expense
Not Designated as Hedging Instrument [Member] | Interest Rate Caps [Member] | 1.00% Strike Rate Derivatives [Member]
Derivative [Line Items]
Derivative Maturity Period			Oct 2014
Strike Rate	1.00%		1.00%
Notional Amount of Hedge	5,754		5,754
Cost of Hedge			174
Estimated Fair Value			1
Change in Cap Valuations Included in Interest Expense