Significant Accounting Policies Accounting Policies (Notes)	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) as set forth in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) and applicable regulations of the Securities and Exchange Commission (“SEC”), but do not include all of the information and footnotes required for complete financial statements. The condensed consolidated balance sheet as of December 31, 2019 was derived from the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of management, the accompanying unaudited condensed consolidated financial statements for the periods presented reflect all adjustments of a normal, recurring nature necessary to fairly state our financial position, results of operations and cash flows. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Operating results for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 or subsequent periods due to seasonal variations and other factors, such as the effects of novel coronavirus (“COVID-19”) and its influence on our future results. Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Green Brick Partners, Inc., its controlled subsidiaries, and variable interest entities (“VIEs”) in which Green Brick Partners, Inc. or one of its controlled subsidiaries is deemed to be the primary beneficiary (together, the “Company”, “we”, or “Green Brick”). All intercompany balances and transactions have been eliminated in consolidation. The Company uses the equity method of accounting for its investments in unconsolidated entities over which it exercises significant influence but does not have a controlling interest. Under the equity method, the Company’s share of the unconsolidated entities’ earnings or losses, if any, is included in the condensed consolidated statements of income. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management of the Company to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes, including the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates. Reclassifications Beginning in the first quarter of 2020, the Company reclassified the write-offs of option deposits and pre-acquisition costs from selling, general and administrative expenses to other (loss) income, net in the consolidated statements of income in order to be more comparable with its peers. There was no impact on net income from the reclassification in any period. For a complete set of the Company’s significant accounting policies, refer to Note 1 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Newly identified significant accounting policies during the three months ended March 31, 2020 are presented below. Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less at the time of purchase to be cash equivalents. Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which changes the impairment model for most financial assets and certain other instruments from an “incurred loss” approach to an “expected credit loss” methodology. The Company adopted the standard on January 1, 2020 using the full retrospective application. The adoption of ASU 2016-13 had no impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which removes Step 2 of the goodwill impairment test. A goodwill impairment will now be determined by the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The Company adopted the standard on January 1, 2020. The adoption of ASU 2017-04 had no impact on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in ASC 740, Income Taxes related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for annual reporting periods, and interim periods therein, beginning after December 15, 2020, with early adoption permitted. The Company does not expect the adoption of ASU 2019-12 to have a material impact on the Company’s consolidated financial statements.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Green Brick Partners, Inc., its controlled subsidiaries, and variable interest entities (“VIEs”) in which Green Brick Partners, Inc. or one of its controlled subsidiaries is deemed to be the primary beneficiary (together, the “Company”, “we”, or “Green Brick”). All intercompany balances and transactions have been eliminated in consolidation.
Equity Method Investments [Policy Text Block]	The Company uses the equity method of accounting for its investments in unconsolidated entities over which it exercises significant influence but does not have a controlling interest. Under the equity method, the Company’s share of the unconsolidated entities’ earnings or losses, if any, is included in the condensed consolidated statements of income.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which changes the impairment model for most financial assets and certain other instruments from an “incurred loss” approach to an “expected credit loss” methodology. The Company adopted the standard on January 1, 2020 using the full retrospective application. The adoption of ASU 2016-13 had no impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which removes Step 2 of the goodwill impairment test. A goodwill impairment will now be determined by the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The Company adopted the standard on January 1, 2020. The adoption of ASU 2017-04 had no impact on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in ASC 740, Income Taxes related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for annual reporting periods, and interim periods therein, beginning after December 15, 2020, with early adoption permitted. The Company does not expect the adoption of ASU 2019-12 to have a material impact on the Company’s consolidated financial statements.
Reclassifications	Reclassifications Beginning in the first quarter of 2020, the Company reclassified the write-offs of option deposits and pre-acquisition costs from selling, general and administrative expenses to other (loss) income, net in the consolidated statements of income in order to be more comparable with its peers. There was no impact on net income from the reclassification in any period.

Significant Accounting Policies Accounting Policies (Notes)

3 Months Ended

Mar. 31, 2020

Significant Accounting Policies [Text Block]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) as set forth in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) and applicable regulations of the Securities and Exchange Commission (“SEC”), but do not include all of the information and footnotes required for complete financial statements. The condensed consolidated balance sheet as of December 31, 2019 was derived from the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of management, the accompanying unaudited condensed consolidated financial statements for the periods presented reflect all adjustments of a normal, recurring nature necessary to fairly state our financial position, results of operations and cash flows. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.

Operating results for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 or subsequent periods due to seasonal variations and other factors, such as the effects of novel coronavirus (“COVID-19”) and its influence on our future results.

Principles of Consolidation

The accompanying unaudited condensed consolidated financial statements include the accounts of Green Brick Partners, Inc., its controlled subsidiaries, and variable interest entities (“VIEs”) in which Green Brick Partners, Inc. or one of its controlled subsidiaries is deemed to be the primary beneficiary (together, the “Company”, “we”, or “Green Brick”).

All intercompany balances and transactions have been eliminated in consolidation.

The Company uses the equity method of accounting for its investments in unconsolidated entities over which it exercises significant influence but does not have a controlling interest. Under the equity method, the Company’s share of the unconsolidated entities’ earnings or losses, if any, is included in the condensed consolidated statements of income.

Use of Estimates

The preparation of the condensed consolidated financial statements in conformity with GAAP requires management of the Company to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes, including the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates.

Reclassifications

Beginning in the first quarter of 2020, the Company reclassified the write-offs of option deposits and pre-acquisition costs from selling, general and administrative expenses to other (loss) income, net in the consolidated statements of income in order to be more comparable with its peers. There was no impact on net income from the reclassification in any period.

For a complete set of the Company’s significant accounting policies, refer to Note 1 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Newly identified significant accounting policies during the three months ended March 31, 2020 are presented below.

Cash and Cash Equivalents

The Company considers all highly liquid investments with original maturities of three months or less at the time of purchase to be cash equivalents.

Recent Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which changes the impairment model for most financial assets and

certain other instruments from an “incurred loss” approach to an “expected credit loss” methodology. The Company adopted the standard on January 1, 2020 using the full retrospective application. The adoption of ASU 2016-13 had no impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which removes Step 2 of the goodwill impairment test. A goodwill impairment will now be determined by the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The Company adopted the standard on January 1, 2020. The adoption of ASU 2017-04 had no impact on the Company’s consolidated financial statements.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in ASC 740, Income Taxes related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for annual reporting periods, and interim periods therein, beginning after December 15, 2020, with early adoption permitted. The Company does not expect the adoption of ASU 2019-12 to have a material impact on the Company’s consolidated financial statements.

Principles of Consolidation

All intercompany balances and transactions have been eliminated in consolidation.

Equity Method Investments [Policy Text Block]

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

Reclassifications