Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of debt facilities.

+ References

No definition available.

+ Details

Name:	wd_DebtInstrumentNumberOfFacilities
Namespace Prefix:	wd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum committed borrowing capacity under a credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

No definition available.

+ Details

Name:	wd_LineOfCreditFacilityCommittedBorrowingCapacity
Namespace Prefix:	wd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum uncommitted borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

No definition available.

+ Details

Name:	wd_LineOfCreditFacilityUncommittedBorrowingCapacity
Namespace Prefix:	wd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

WAREHOUSE NOTES PAYABLE - Summary Information (Detail) $ in Thousands	3 Months Ended			6 Months Ended
	Sep. 30, 2019 loan	Jun. 30, 2019 USD ($)	Mar. 31, 2019	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Warehouse notes payable
Committed Amount		$ 2,465,000		$ 2,465,000
Uncommitted Amount		2,440,000		2,440,000
Total Facility Capacity		4,905,000		4,905,000
Outstanding Balance		1,313,955		1,313,955	$ 1,161,382
Debt issuance costs		$ (741)		(741)
Agency Warehouse Facility #6 \| Agency Warehouse Facility
Warehouse notes payable
Maturity date			Jan. 31, 2020
Interim Warehouse Facility #1 \| Interim Warehouse Facility
Warehouse notes payable
Maturity date		Apr. 30, 2020
Interim Warehouse Facility #3 \| Interim Warehouse Facility
Warehouse notes payable
Maturity date		May 18, 2020
Interim Warehouse Facility #4 \| Interim Warehouse Facility
Warehouse notes payable
Maturity date		Apr. 30, 2020
Loans Held for Sale \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 2,055,000		2,055,000
Uncommitted Amount		2,365,000		2,365,000
Total Facility Capacity		4,420,000		4,420,000
Outstanding Balance		1,162,664		1,162,664
Loans Held for Sale \| Agency Warehouse Facility #1 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		425,000		425,000
Uncommitted Amount		200,000		200,000
Total Facility Capacity		625,000		625,000
Outstanding Balance		223,559		$ 223,559
Loans Held for Sale \| Agency Warehouse Facility #1 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate	1.15%			1.20%
Loans Held for Sale \| Agency Warehouse Facility #2 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		500,000		$ 500,000
Uncommitted Amount		300,000		300,000
Total Facility Capacity		800,000		800,000
Outstanding Balance		$ 215,114		$ 215,114
Loans Held for Sale \| Agency Warehouse Facility #2 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate		1.15%		1.15%
Loans Held for Sale \| Agency Warehouse Facility #3 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 500,000		$ 500,000
Uncommitted Amount		265,000		265,000
Total Facility Capacity		765,000		765,000
Outstanding Balance		$ 208,322		$ 208,322
Maturity date		Apr. 30, 2020
Loans Held for Sale \| Agency Warehouse Facility #3 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate		1.15%		1.15%
Loans Held for Sale \| Agency Warehouse Facility #4 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 350,000		$ 350,000
Total Facility Capacity		350,000		350,000
Outstanding Balance		$ 256,328		$ 256,328
Loans Held for Sale \| Agency Warehouse Facility #4 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate		1.15%		1.15%
Loans Held for Sale \| Agency Warehouse Facility #5 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 30,000		$ 30,000
Total Facility Capacity		30,000		30,000
Outstanding Balance		5,777		$ 5,777
Loans Held for Sale \| Agency Warehouse Facility #5 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate				1.80%
Loans Held for Sale \| Agency Warehouse Facility #6 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		250,000		$ 250,000
Uncommitted Amount		100,000		100,000
Total Facility Capacity		350,000		350,000
Outstanding Balance		130,961		$ 130,961
Loans Held for Sale \| Agency Warehouse Facility #6 \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate				1.20%
Loans Held for Investment \| Interim Warehouse Facility #1 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		135,000		$ 135,000
Total Facility Capacity		135,000		135,000
Outstanding Balance		87,700		$ 87,700
Loans Held for Investment \| Interim Warehouse Facility #1 \| Interim Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate				1.90%
Loans Held for Investment \| Interim Warehouse Facility #2 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		100,000		$ 100,000
Total Facility Capacity		100,000		100,000
Outstanding Balance		41,082		$ 41,082
Loans Held for Investment \| Interim Warehouse Facility #2 \| Interim Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate				2.00%
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		75,000		$ 75,000
Uncommitted Amount		75,000		75,000
Total Facility Capacity		150,000		150,000
Outstanding Balance		23,250		$ 23,250
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility \| LIBOR \| Minimum
Warehouse notes payable
Basis points added to reference rate				1.90%
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility \| LIBOR \| Maximum
Warehouse notes payable
Basis points added to reference rate				2.50%
Loans Held for Investment \| Interim Warehouse Facility #4 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		100,000		$ 100,000
Total Facility Capacity		100,000		$ 100,000
Loans Held for Investment \| Interim Warehouse Facility #4 \| Interim Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit				30-day LIBOR
Basis points added to reference rate				1.75%
National Banks \| Agency Warehouse Facility
Warehouse notes payable
Number of warehouse credit facilities \| loan	5
Total Facility Capacity		2,900,000		$ 2,900,000
National Banks \| Interim Warehouse Facility
Warehouse notes payable
Total Facility Capacity		500,000		500,000
National Banks \| Loans Held for Sale \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		2,055,000		2,055,000
Uncommitted Amount		865,000		865,000
Total Facility Capacity		2,920,000		2,920,000
Outstanding Balance		1,040,061		1,040,061
National Banks \| Loans Held for Investment \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		410,000		410,000
Uncommitted Amount		75,000		75,000
Total Facility Capacity		485,000		485,000
Outstanding Balance		152,032		152,032
Fannie Mae \| Loans Held for Sale \| Uncommitted Agency Warehouse Facility \| Agency Warehouse Facility
Warehouse notes payable
Uncommitted Amount		1,500,000		1,500,000
Total Facility Capacity		1,500,000		1,500,000
Outstanding Balance		$ 122,603		$ 122,603