Derivative Financial Instruments (Interest Rate Cap Derivative Summary) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	$ 225,000
Interest Rate Cap Seventy Seven Million Notional May Two Thousand Fifteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	77,000
Fair Value as of End of Period	17
Interest Rate Cap Two Hundred Fifteen Million Notional May Two Thousand Sixteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	215,000
Fair Value as of End of Period	685
Interest Rate Cap Ninety Six Million Five Hundred Thirty Thousand Notional April Two Thousand Fifteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	96,530
Fair Value as of End of Period	20
Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	216,500
Fair Value as of End of Period	1,117
Interest Rate Cap One Hundred Million Notional August Two Thousand Sixteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	100,000
Fair Value as of End of Period	602
Interest Rate Cap One Hundred Million Notional March Two Thousand Seventeen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	100,000
Fair Value as of End of Period	1,199
Interest Rate Cap Seventy Five Million Notional November Two Thousand Sixteen Maturity [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	75,000
Fair Value as of End of Period	607
Total Interest Rate Cap [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	1,030,030
Fair Value as of End of Period	5,985
Cash Flow Hedging [Member] | Interest Rate Cap Twenty Million Notional September Two Thousand Fourteen Maturity [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	20,000
Fair Value as of End of Period	0
Cash Flow Hedging [Member] | Interest Rate Cap Forty Million Notional September Two Thousand Fourteen Maturity [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	40,000
Fair Value as of End of Period	0
Cash Flow Hedging [Member] | Interest Rate Cap Fifty Million Notional September Two Thousand Seventeen Maturity [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	50,000
Fair Value as of End of Period	951
Cash Flow Hedging [Member] | Interest Rate Cap Forty Million Notional September Two Thousand Seventeen Maturity [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	40,000
Fair Value as of End of Period	787
Cash Flow Hedging [Member] | Total Interest Rate Cap [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Notional Amount	150,000
Fair Value as of End of Period	$ 1,738