Deferred costs and other intangibles - Deferred costs and other intangibles (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
Acquired Indefinite-lived Intangible Assets [Line Items]
Deferred leasing costs	$ 9,164
Deferred financing costs	12,092
Intangible assets:
Intangible assets	32,541
Less: accumulated amortization	(8,023)
Total	24,518
Value of In-place Leases [Member]
Intangible assets:
Intangible assets	6,085
Total	4,356
Trademark [Member]
Intangible assets:
Intangible assets	3,100
Total	2,895
Database [Member]
Intangible assets:
Intangible assets	2,100
Total	$ 2,007