Interest Rate Derivative Instruments - Additional Information (Detail) (QualityTech, LP [Member], USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Interest Rate Swap [Member]	Sep. 30, 2012 Interest Rate Swap [Member]	Sep. 30, 2013 Interest Rate Swap [Member]	Sep. 30, 2012 Interest Rate Swap [Member]	Sep. 30, 2013 Fair Value Measurements, Level 2 [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Fair Value Measurements, Level 2 [Member] Interest Rate Swap [Member]	Sep. 30, 2013 Cash Flow Hedging [Member]	Sep. 30, 2012 Cash Flow Hedging [Member]	Sep. 30, 2013 Cash Flow Hedging [Member]	Sep. 30, 2012 Cash Flow Hedging [Member]	Sep. 30, 2013 Cash Flow Hedging [Member] Interest Rate Cap [Member]	Feb. 08, 2012 Cash Flow Hedging [Member] Interest Rate Cap [Member]	Sep. 30, 2013 Cash Flow Hedging [Member] Interest Rate Cap [Member] LIBOR [Member]	Feb. 29, 2012 Cash Flow Hedging [Member] Interest Rate Swap [Member]	Feb. 08, 2012 Cash Flow Hedging [Member] Interest Rate Swap [Member]
Derivative [Line Items]
Derivative instruments, notional amount															$ 50,000,000	$ 150,000,000		$ 150,000,000	$ 150,000,000
Capped LIBOR rate																	3.00%
Unrealized gains or losses on cash flow hedge derivative effective portion											0	400,000	200,000	800,000
Interest expense related to payments on interest rate swaps	4,343,000	6,646,000	15,977,000	19,039,000	100,000	0	400,000	500,000
Interest rate swap liability recorded at fair value									$ 500,000	$ 800,000