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

No definition available.

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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.

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No definition available.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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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.

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- Definition

Amount of the fee for available but unused credit capacity under the credit facility.

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

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The effective interest rate at the end of the reporting period.

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- 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.

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No definition available.

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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.

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- Definition

Represents the stated variable base rate percentage floor when determining variable rate options under the terms of a debt agreement.

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No definition available.

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Represents the advance under the credit facility as a percentage of loans made by the reporting entity.

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No definition available.

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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.

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No definition available.

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Temporary increase in maximum borrowing capacity under the credit facility.

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No definition available.

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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.

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No definition available.

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DEBT - Summary Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Warehouse notes payable
Outstanding Balance		$ 937,769	$ 1,990,183
Debt issuance costs		$ (1,731)	$ (1,928)
LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit		30-day LIBOR	30-day LIBOR
Interest rate at end of period (as a percent)		1.56%	0.77%
Warehouse Facilities
Warehouse notes payable
Committed Amount		$ 2,295,000	$ 2,095,000
Uncommitted Amount		2,350,000	1,500,000
Temporary Increase		400,000	400,000
Total Facility Capacity		5,045,000	3,995,000
Outstanding Balance		937,769	1,990,183
Interest expense		52,000	36,600	$ 29,200
Facility fees		$ 4,600	5,500	4,500
Agency Warehouse Facility #1
Warehouse notes payable
Maturity date		Oct. 29, 2018
Advances made as a percentage of the loan balance		100.00%
Agency Warehouse Facility #2
Warehouse notes payable
Maturity date		Sep. 10, 2018
Advances made as a percentage of the loan balance		100.00%
Agency Warehouse Facility #3
Warehouse notes payable
Maturity date		Apr. 30, 2018
Advances made as a percentage of the loan balance		100.00%
Agency Warehouse Facility #3, Temporary Increase
Warehouse notes payable
Maturity date		Jan. 01, 2018
Agency Warehouse Facility #4
Warehouse notes payable
Maturity date		Oct. 05, 2018
Agency Warehouse Facility #5
Warehouse notes payable
Maturity date		Jul. 12, 2019
Agency Warehouse Facility #6
Warehouse notes payable
Maturity date		Sep. 18, 2018
Agency Warehouse Facility #7
Warehouse notes payable
Committed Amount	$ 250,000
Uncommitted Amount	$ 100,000
Maturity date	Feb. 02, 2019
Advances made as a percentage of the loan balance	100.00%
Agency Warehouse Facility #7 \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit	LIBOR
Basis points added to reference rate	1.30%
Interim Warehouse Facility #1
Warehouse notes payable
Term of facility		3 years
Maturity date		Apr. 30, 2018
Interim Warehouse Facility #2
Warehouse notes payable
Term of facility		3 years
Maturity date		Dec. 13, 2019
Interim Warehouse Facility #3
Warehouse notes payable
Term of facility		3 years
Maturity date		May 19, 2018
Loans Held for Sale
Warehouse notes payable
Interest expense		$ 46,221	31,278	23,134
Loans Held for Sale \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		2,035,000	1,735,000
Uncommitted Amount		2,350,000	1,500,000
Temporary Increase		400,000	400,000
Total Facility Capacity		4,785,000	3,635,000
Outstanding Balance		893,954	1,848,994
Loans Held for Sale \| Agency Warehouse Facility #1 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		425,000	425,000
Uncommitted Amount		300,000
Total Facility Capacity		725,000	425,000
Outstanding Balance		$ 100,188	$ 109,087
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	30-day LIBOR
Basis points added to reference rate		1.30%	1.40%
Loans Held for Sale \| Agency Warehouse Facility #2 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 500,000	$ 650,000
Uncommitted Amount		300,000
Total Facility Capacity		800,000	650,000
Outstanding Balance		$ 346,291	$ 274,181
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	30-day LIBOR
Basis points added to reference rate		1.30%	1.40%
Loans Held for Sale \| Agency Warehouse Facility #3 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 480,000	$ 280,000
Temporary Increase		400,000	400,000
Total Facility Capacity		880,000	680,000
Outstanding Balance		$ 44,619	$ 320,801
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	30-day LIBOR
Basis points added to reference rate		1.25%	1.35%
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		$ 129,787	$ 186,869
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	30-day LIBOR
Basis points added to reference rate		1.30%	1.40%
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		$ 19,057	$ 14,551
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	30-day LIBOR
Basis points added to reference rate		1.80%	1.80%
Loans Held for Sale \| Agency Warehouse Facility #6 \| Agency Warehouse Facility
Warehouse notes payable
Committed Amount		$ 250,000
Uncommitted Amount		250,000
Total Facility Capacity		500,000
Outstanding Balance		$ 130,859
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		1.35%
Loans Held for Investment
Warehouse notes payable
Interest expense		$ 5,828	$ 5,326	$ 6,037
Loans Held for Investment \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		260,000	360,000
Total Facility Capacity		260,000	360,000
Outstanding Balance		45,546	143,117
Loans Held for Investment \| Interim Warehouse Facility #1 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		85,000	85,000
Total Facility Capacity		85,000	85,000
Outstanding Balance		$ 10,290	$ 36,916
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	30-day LIBOR
Basis points added to reference rate		1.90%	1.90%
Loans Held for Investment \| Interim Warehouse Facility #2 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		$ 100,000	$ 200,000
Total Facility Capacity		100,000	200,000
Outstanding Balance		$ 24,662	$ 70,196
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	30-day LIBOR
Basis points added to reference rate		2.00%	2.00%
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility
Warehouse notes payable
Committed Amount		$ 75,000	$ 75,000
Total Facility Capacity		75,000	75,000
Outstanding Balance		$ 10,594	$ 36,005
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	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		2.00%	2.00%
Loans Held for Investment \| Interim Warehouse Facility #3 \| Interim Warehouse Facility \| LIBOR \| Maximum
Warehouse notes payable
Basis points added to reference rate		2.50%	2.50%
National Banks \| Agency Warehouse Facility
Warehouse notes payable
Total Facility Capacity		$ 3,300,000
National Banks \| Interim Warehouse Facility
Warehouse notes payable
Total Facility Capacity		$ 300,000
Fannie Mae \| Uncommitted Agency Warehouse Facility
Warehouse notes payable
Advances made as a percentage of the loan balance		99.00%
Fannie Mae \| Uncommitted Agency Warehouse Facility \| LIBOR \| Minimum
Warehouse notes payable
Minimum variable base rate percentage under terms of the debt agreement		0.35%
Fannie Mae \| Uncommitted Agency Warehouse Facility \| Agency Warehouse Facility
Warehouse notes payable
Total Facility Capacity		$ 1,500,000
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		$ 123,153	$ 943,505
Fannie Mae \| Loans Held for Sale \| Uncommitted Agency Warehouse Facility \| Agency Warehouse Facility \| LIBOR
Warehouse notes payable
Reference rate for variable interest on the line of credit		30-day LIBOR	30-day LIBOR
Basis points added to reference rate		1.15%	1.15%