Investments in and Advances to Joint Ventures - Service Fees and Income Earned by Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Equity Method Investments And Joint Ventures [Abstract]
Management and other fees	$ 9.6	$ 6.5	$ 15.8	$ 12.8
Development fees and leasing commissions	1.8	1.6	3.7	3.2
Interest income	$ 8.3	$ 6.4	$ 16.6	$ 12.7

Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_ManagementFeesRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration