Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Interest Rate Caps [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value		180
Valuation Technique		Discounted cash flow
Interest Rate Caps [Member] | Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	126
Valuation Technique	Discounted cash flow
Minimum [Member] | Interest Rate Caps [Member] | Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	0.49%	0.49%
Maximum [Member] | Interest Rate Caps [Member] | Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	1.18%	1.18%
Loans Held For Sale, at Fair Value [Member] | Comparable Sales
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	1,608
Valuation Technique	Comparable sales
Loans Held For Sale, at Fair Value [Member] | Minimum [Member] | Comparable Sales
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Time Discount	0.00%
Loans Held For Sale, at Fair Value [Member] | Maximum [Member] | Comparable Sales
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Time Discount	1.50%