Derivative Financial Instruments Derivative Financial Instruments (Interest Rate Cap Derivative Summary) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Interest Rate Cap Seventy Seven Million Notional May Two Thousand Fifteen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	$ 77,000
Fair Value as of End of Period	0
Interest Rate Cap Two Hundred Fifteen Million Notional May Two Thousand Sixteen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	215,000
Fair Value as of End of Period	17
Interest Rate Cap Ninety Six Million Five Hundred Thirty Thousand Notional April Two Thousand Fifteen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	96,530
Fair Value as of End of Period	0
Interest Rate Cap Fifty Six Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	56,500
Fair Value as of End of Period	34
Interest Rate Cap One Hundred Million Notional March Two Thousand Seventeen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	100,000
Fair Value as of End of Period	275
Interest Rate Cap Seventy Five Million Notional November Two Thousand Sixteen Maturity | Not Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	75,000
Fair Value as of End of Period	95
Total Interest Rate Cap
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	970,030
Fair Value as of End of Period	1,089
Cash Flow Hedging | Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity | Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	216,500
Fair Value as of End of Period	89
Cash Flow Hedging | Interest Rate Cap Forty Three Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity | Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	43,500
Fair Value as of End of Period	26
Cash Flow Hedging | Interest Rate Cap Fifty Million Notional September Two Thousand Seventeen Maturity | Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	50,000
Fair Value as of End of Period	299
Cash Flow Hedging | Interest Rate Cap Forty Million Notional September Two Thousand Seventeen Maturity | Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	40,000
Fair Value as of End of Period	254
Cash Flow Hedging | Total Interest Rate Cap | Designated as Hedging Instrument
Interest Rate Cap Derivative Summary [Line Items]
Notional amount	350,000
Fair Value as of End of Period	$ 668