Customer Leases, as Lessor - Future Minimum Lease Payments to Be Received Under Non Cancelable Operating Customer Leases (Detail) (QualityTech, LP [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
QualityTech, LP [Member]
Operating Leased Assets [Line Items]
2013 (October - December)	$ 33,483
2014	131,120
2015	100,654
2016	71,404
2017	51,762
Thereafter	91,383
Total	$ 479,806