Real Estate (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Real Estate [Abstract]
Properties in operation	$ 196,980wrb_BuildingandLeaseObligations	$ 283,393wrb_BuildingandLeaseObligations
Properties under development	534,632us-gaap_DevelopmentInProcess	431,849us-gaap_DevelopmentInProcess
Total	$ 731,612us-gaap_RealEstateInvestmentPropertyNet	$ 715,242us-gaap_RealEstateInvestmentPropertyNet

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_RealEstateInvestmentPropertyNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant