LITIGATION, COMMITMENTS, AND CONTINGENCIES - Other Commitments (Detail) - Preferred Equity Investments $ in Millions	Jun. 30, 2017 USD ($)
Other Commitments
Investment commitments	$ 42.8
Investment commitment, funded	$ 36.2

Amount of other commitment funded as of the end of the reporting period not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	wd_OtherCommitmentFundedAmount
Namespace Prefix:	wd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant