Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles ("GAAP"). The condensed consolidated financial statements include the financial position and results of operations of the Company and its consolidated subsidiaries, including the Operating Partnership, its wholly-owned subsidiaries, and any interests in variable interest entities ("VIEs") where the Company has been determined to be the primary beneficiary. All significant intercompany transactions and balances have been eliminated in consolidation. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting of normal recurring accruals, which are necessary for the fair presentation of the financial condition and results of operations for the interim periods presented. The accompanying condensed consolidated financial statements were prepared in accordance with the requirements for interim financial information. Accordingly, these interim financial statements have not been audited and exclude certain disclosures required for annual financial statements. Also, the operating results presented for interim periods are not necessarily indicative of the results that may be expected for any other interim period or for the entire year. These interim financial statements should be read in conjunction with the audited consolidated financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed. Such estimates are based on management’s historical experience and best judgment after considering past, current, and expected events and economic conditions. Actual results could differ significantly from management’s estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Leases On February 25, 2016, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update ("ASU") that requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets (ASU 2016-02—Leases (Topic 842)). The new standard also makes targeted changes to lessor accounting. The Company adopted the new standard on January 1, 2019, using the modified retrospective approach for all leases existing at, or entered into after, the beginning of the earliest comparative period presented as permitted in Accounting Standards Codification ("ASC") Topic 842. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard, which allowed the Company to not reassess whether any expired or existing contracts are or contain leases, not reassess the lease classification for any expired or existing leases, and not reassess initial direct costs for existing leases. As of January 1, 2019, Company did not have any leases classified as finance leases. The Company also elected a practical expedient that allowed it to not separate non-lease components from lease components and instead to account for each lease and non-lease component as a single lease component. The adoption of the new standard as of January 1, 2019 did not impact the Company's consolidated results of operations and had no impact on cash flows. As a lessee, the Company had six ground leases on five properties as of January 1, 2019 with initial terms that range from 20 to 65 years and options to extend up to an additional 70 years in certain cases. The exercise of lease renewal options is at the Company's sole discretion. The depreciable life of assets and leasehold improvements are limited by the expected lease term. The Company recognizes lease expense for operating leases on a straight-line basis over the lease term. The Company's lease agreements do not contain any residual value guarantees or material restrictive covenants. The long-term ground leases represent a majority of the Company's current operating lease payments. The Company recorded right-of-use assets totaling $32.2 million and lease liabilities totaling $41.4 million upon adopting this standard on January 1, 2019. The Company utilized a weighted average discount rate of 5.4% to measure its lease liabilities upon adoption. As a lessor, the Company leases its properties under operating leases and recognizes base rents on a straight-line basis over the lease term. The Company also recognizes revenue from tenant recoveries, through which tenants reimburse the Company on an accrual basis for certain expenses such as utilities, janitorial services, repairs and maintenance, security and alarms, parking lot and ground maintenance, administrative services, management fees, insurance, and real estate taxes. Rental revenues are reduced by the amount of any leasing incentives amortized on a straight-line basis over the term of the applicable lease. In addition, the Company recognizes contingent rental revenue (e.g., percentage rents based on tenant sales thresholds) when the sales thresholds are met. Many tenant leases include one or more options to renew, with renewal terms that can extend the lease term from one to 15 years or more. The exercise of lease renewal options is at the tenant's sole discretion. The Company includes a renewal period in the lease term only if it appears at lease inception that the renewal is reasonably assured. The new standard includes new considerations regarding the recognition of rental revenue when collection is not probable. The Company changed its presentation and measurement of charges for uncollectable lease revenue associated with its office, retail, and residential leasing activity, reflecting those amounts as a component of rental income on the accompanying Condensed Consolidated Statement of Comprehensive Income for the three and six months ended June 30, 2019. However, in accordance with its prospective adoption of the standard, the Company did not adjust the prior year period presentation of charges for uncollectable lease revenue associated with its office, retail, and residential leasing activity as a component of operating expenses, excluding property taxes, on the accompanying Condensed Consolidated Statement of Comprehensive Income for the three and six months ended June 30, 2018. Instead, the Company recorded a combined adjustment of $0.2 million to the opening balances for distributions in excess of earnings and noncontrolling interest relating to receivables where collection of substantially all operating lease payments was not probable as of January 1, 2019. Lease-related receivables, which include contractual amounts accrued and unpaid from tenants and accrued straight-line rents receivable, are reduced for credit losses. Such amounts are recognized as a reduction to real estate rental revenues. The Company evaluates the collectability of lease receivables using several factors, including a lessee’s creditworthiness. The Company recognizes a credit loss on lease-related receivables when, in the opinion of management, collection of substantially all lease payments is not probable. When collectability is determined not probable, any lease income subsequent to recognizing the credit loss is limited to the lesser of the lease income reflected on a straight-line basis or cash collected. Credit losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses - Measurement of Credit Losses on Financial Instruments (Topic 326). ASU 2016-13 significantly changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance will replace the "incurred loss" approach under existing guidance with an "expected loss" model for instruments measured at amortized cost, such as our notes receivable. The guidance is effective for fiscal years beginning after December 15, 2019 and is to be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. While the Company is currently evaluating the impact ASU 2016-13 will have on the consolidated financial statements, the Company expects that the adoption could result in earlier recognition of a provision for loan losses on its notes receivable.
Segments	Segments Net operating income (segment revenues minus segment expenses) is the measure used by the Company’s chief operating decision-maker to assess segment performance. Net operating income is not a measure of operating income or cash flows from operating activities as measured by GAAP and is not indicative of cash available to fund cash needs. As a result, net operating income should not be considered an alternative to cash flows as a measure of liquidity. Not all companies calculate net operating income in the same manner. The Company considers net operating income to be an appropriate supplemental measure to net income because it assists both investors and management in understanding the core operations of the Company’s real estate and construction businesses.
Construction Contracts	The Company defers pre-contract costs when such costs are directly associated with specific anticipated contracts and their recovery is probable.Construction Contracts Construction contract costs and estimated earnings in excess of billings represent reimbursable costs and amounts earned under contracts in progress as of the balance sheet date. Such amounts become billable according to contract terms, which usually consider the passage of time, achievement of certain milestones, or completion of the project. The Company expects to bill and collect substantially all construction contract costs and estimated earnings in excess of billings as of June 30, 2019 during the next twelve months. Billings in excess of construction contract costs and estimated earnings represent billings or collections on contracts made in advance of revenue recognized.
Derivative Financial Instruments	Derivative Financial Instruments The Company may enter into interest rate derivative contracts to manage exposure to interest rate risks. The Company does not use derivative financial instruments for trading or speculative purposes. Derivative financial instruments are recognized at fair value and presented within other assets and other liabilities in the condensed consolidated balance sheets. Gains and losses resulting from changes in the fair value of derivatives that are neither designated nor qualify as hedging instruments are recognized within the change in fair value of interest rate derivatives in the condensed consolidated statements of comprehensive income. For derivatives that qualify as cash flow hedges, the gain or loss is reported as a component of other comprehensive income (loss) and reclassified into earnings in the periods during which the hedged forecasted transaction affects earnings.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value measurements are based on assumptions that market participants would use in pricing an asset or a liability. The hierarchy for inputs used in measuring fair value is as follows: Level 1 — quoted prices in active markets for identical assets or liabilities Level 2 — observable inputs other than quoted prices in active markets for identical assets and liabilities Level 3 — unobservable inputs Except as disclosed below, the carrying amounts of the Company’s financial instruments approximate their fair values. Financial assets and liabilities whose fair values are measured on a recurring basis using Level 2 inputs consist of interest rate swaps and caps. The Company measures the fair values of these assets and liabilities based on prices provided by independent market participants that are based on observable inputs using market-based valuation techniques. Financial assets and liabilities whose fair values are not measured at fair value but for which the fair value is disclosed include the Company's notes receivable and indebtedness. The fair value is estimated by discounting the future cash flows of each instrument at estimated market rates consistent with the maturity, credit characteristics, and other terms of the arrangements, which are Level 3 inputs under the fair value hierarchy. In certain cases, the inputs used to estimate the fair value may fall into different levels of the fair value hierarchy. For disclosure purposes, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement. Considerable judgment is used to estimate the fair value of financial instruments. The estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized upon disposition of the financial instruments.
Legal Proceedings	Legal Proceedings The Company is from time to time involved in various disputes, lawsuits, warranty claims, environmental and other matters arising in the ordinary course of business. Management makes assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters. The Company currently is a party to various legal proceedings, none of which management expects will have a material adverse effect on the Company’s financial position, results of operations, or liquidity. Management accrues a liability for litigation if an unfavorable outcome is determined to be probable and the amount of loss can be reasonably estimated. If an unfavorable outcome is determined to be probable and a range of loss can be reasonably estimated, management accrues the best estimate within the range; however, if no amount within the range is a better estimate than any other, the minimum amount within the range is accrued. Legal fees related to litigation are expensed as incurred. Management does not believe that the ultimate outcome of these matters, either individually or in the aggregate, could have a material adverse effect on the Company’s financial position or results of operations; however, litigation is subject to inherent uncertainties. Under the Company’s leases, tenants are typically obligated to indemnify the Company from and against all liabilities, costs, and expenses imposed upon or asserted against it as owner of the properties due to certain matters relating to the operation of the properties by the tenant.

Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2019

The accompanying condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles ("GAAP").

The condensed consolidated financial statements include the financial position and results of operations of the Company and its consolidated subsidiaries, including the Operating Partnership, its wholly-owned subsidiaries, and any interests in variable interest entities ("VIEs") where the Company has been determined to be the primary beneficiary. All significant intercompany transactions and balances have been eliminated in consolidation.

In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting of normal recurring accruals, which are necessary for the fair presentation of the financial condition and results of operations for the interim periods presented.

The accompanying condensed consolidated financial statements were prepared in accordance with the requirements for interim financial information. Accordingly, these interim financial statements have not been audited and exclude certain disclosures required for annual financial statements. Also, the operating results presented for interim periods are not necessarily indicative of the results that may be expected for any other interim period or for the entire year. These interim financial statements should be read in conjunction with the audited consolidated financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed. Such estimates are based on management’s historical experience and best judgment after considering past, current, and expected events and economic conditions. Actual results could differ significantly from management’s estimates.

Recent Accounting Pronouncements

Leases

On February 25, 2016, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update ("ASU") that requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets (ASU 2016-02—Leases (Topic 842)). The new standard also makes targeted changes to lessor accounting. The Company adopted the new standard on January 1, 2019, using the modified retrospective approach for all leases

existing at, or entered into after, the beginning of the earliest comparative period presented as permitted in Accounting Standards Codification ("ASC") Topic 842.

In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard, which allowed the Company to not reassess whether any expired or existing contracts are or contain leases, not reassess the lease classification for any expired or existing leases, and not reassess initial direct costs for existing leases. As of January 1, 2019, Company did not have any leases classified as finance leases. The Company also elected a practical expedient that allowed it to not separate non-lease components from lease components and instead to account for each lease and non-lease component as a single lease component. The adoption of the new standard as of January 1, 2019 did not impact the Company's consolidated results of operations and had no impact on cash flows.

As a lessee, the Company had six ground leases on five properties as of January 1, 2019 with initial terms that range from 20 to 65 years and options to extend up to an additional 70 years in certain cases. The exercise of lease renewal options is at the Company's sole discretion. The depreciable life of assets and leasehold improvements are limited by the expected lease term. The Company recognizes lease expense for operating leases on a straight-line basis over the lease term. The Company's lease agreements do not contain any residual value guarantees or material restrictive covenants.

The long-term ground leases represent a majority of the Company's current operating lease payments. The Company recorded right-of-use assets totaling $32.2 million and lease liabilities totaling $41.4 million upon adopting this standard on January 1, 2019. The Company utilized a weighted average discount rate of 5.4% to measure its lease liabilities upon adoption.

As a lessor, the Company leases its properties under operating leases and recognizes base rents on a straight-line basis over the lease term. The Company also recognizes revenue from tenant recoveries, through which tenants reimburse the Company on an accrual basis for certain expenses such as utilities, janitorial services, repairs and maintenance, security and alarms, parking lot and ground maintenance, administrative services, management fees, insurance, and real estate taxes. Rental revenues are reduced by the amount of any leasing incentives amortized on a straight-line basis over the term of the applicable lease. In addition, the Company recognizes contingent rental revenue (e.g., percentage rents based on tenant sales thresholds) when the sales thresholds are met. Many tenant leases include one or more options to renew, with renewal terms that can extend the lease term from one to 15 years or more. The exercise of lease renewal options is at the tenant's sole discretion. The Company includes a renewal period in the lease term only if it appears at lease inception that the renewal is reasonably assured.

The new standard includes new considerations regarding the recognition of rental revenue when collection is not probable. The Company changed its presentation and measurement of charges for uncollectable lease revenue associated with its office, retail, and residential leasing activity, reflecting those amounts as a component of rental income on the accompanying Condensed Consolidated Statement of Comprehensive Income for the three and six months ended June 30, 2019. However, in accordance with its prospective adoption of the standard, the Company did not adjust the prior year period presentation of charges for uncollectable lease revenue associated with its office, retail, and residential leasing activity as a component of operating expenses, excluding property taxes, on the accompanying Condensed Consolidated Statement of Comprehensive Income for the three and six months ended June 30, 2018. Instead, the Company recorded a combined adjustment of $0.2 million to the opening balances for distributions in excess of earnings and noncontrolling interest relating to receivables where collection of substantially all operating lease payments was not probable as of January 1, 2019.

Lease-related receivables, which include contractual amounts accrued and unpaid from tenants and accrued straight-line rents receivable, are reduced for credit losses. Such amounts are recognized as a reduction to real estate rental revenues. The Company evaluates the collectability of lease receivables using several factors, including a lessee’s creditworthiness. The Company recognizes a credit loss on lease-related receivables when, in the opinion of management, collection of substantially all lease payments is not probable. When collectability is determined not probable, any lease income subsequent to recognizing the credit loss is limited to the lesser of the lease income reflected on a straight-line basis or cash collected.

Credit losses

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses - Measurement of Credit Losses on Financial Instruments (Topic 326). ASU 2016-13 significantly changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance will replace the "incurred loss" approach under existing guidance with an "expected loss" model for instruments measured at

amortized cost, such as our notes receivable. The guidance is effective for fiscal years beginning after December 15, 2019 and is to be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. While the Company is currently evaluating the impact ASU 2016-13 will have on the consolidated financial statements, the Company expects that the adoption could result in earlier recognition of a provision for loan losses on its notes receivable.

Segments

Net operating income (segment revenues minus segment expenses) is the measure used by the Company’s chief operating decision-maker to assess segment performance. Net operating income is not a measure of operating income or cash flows from operating activities as measured by GAAP and is not indicative of cash available to fund cash needs. As a result, net operating income should not be considered an alternative to cash flows as a measure of liquidity. Not all companies calculate net operating income in the same manner. The Company considers net operating income to be an appropriate supplemental measure to net income because it assists both investors and management in understanding the core operations of the Company’s real estate and construction businesses.

Construction Contracts

The Company defers pre-contract costs when such costs are directly associated with specific anticipated contracts and their recovery is probable.Construction Contracts

Construction contract costs and estimated earnings in excess of billings represent reimbursable costs and amounts earned under contracts in progress as of the balance sheet date. Such amounts become billable according to contract terms, which usually consider the passage of time, achievement of certain milestones, or completion of the project. The Company expects to bill and collect substantially all construction contract costs and estimated earnings in excess of billings as of June 30, 2019 during the next twelve months.

Billings in excess of construction contract costs and estimated earnings represent billings or collections on contracts made in advance of revenue recognized.

Derivative Financial Instruments

The Company may enter into interest rate derivative contracts to manage exposure to interest rate risks. The Company does not use derivative financial instruments for trading or speculative purposes. Derivative financial instruments are recognized at fair value and presented within other assets and other liabilities in the condensed consolidated balance sheets. Gains and losses resulting from changes in the fair value of derivatives that are neither designated nor qualify as hedging instruments are recognized within the change in fair value of interest rate derivatives in the condensed consolidated statements of comprehensive income. For derivatives that qualify as cash flow hedges, the gain or loss is reported as a component of other comprehensive income (loss) and reclassified into earnings in the periods during which the hedged forecasted transaction affects earnings.

Fair Value of Financial Instruments

Fair value measurements are based on assumptions that market participants would use in pricing an asset or a liability. The hierarchy for inputs used in measuring fair value is as follows:

Level 1 — quoted prices in active markets for identical assets or liabilities

Level 2 — observable inputs other than quoted prices in active markets for identical assets and liabilities

Level 3 — unobservable inputs

Except as disclosed below, the carrying amounts of the Company’s financial instruments approximate their fair values. Financial assets and liabilities whose fair values are measured on a recurring basis using Level 2 inputs consist of interest rate swaps and caps. The Company measures the fair values of these assets and liabilities based on prices provided by independent market participants that are based on observable inputs using market-based valuation techniques.

Financial assets and liabilities whose fair values are not measured at fair value but for which the fair value is disclosed include the Company's notes receivable and indebtedness. The fair value is estimated by discounting the future cash flows of each instrument at estimated market rates consistent with the maturity, credit characteristics, and other terms of the arrangements, which are Level 3 inputs under the fair value hierarchy.

In certain cases, the inputs used to estimate the fair value may fall into different levels of the fair value hierarchy. For disclosure purposes, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement.

Considerable judgment is used to estimate the fair value of financial instruments. The estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized upon disposition of the financial instruments.

Legal Proceedings

The Company is from time to time involved in various disputes, lawsuits, warranty claims, environmental and other matters arising in the ordinary course of business. Management makes assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters.

The Company currently is a party to various legal proceedings, none of which management expects will have a material adverse effect on the Company’s financial position, results of operations, or liquidity. Management accrues a liability for litigation if an unfavorable outcome is determined to be probable and the amount of loss can be reasonably estimated. If an unfavorable outcome is determined to be probable and a range of loss can be reasonably estimated, management accrues the best estimate within the range; however, if no amount within the range is a better estimate than any other, the minimum amount within the range is accrued. Legal fees related to litigation are expensed as incurred. Management does not believe that the ultimate outcome of these matters, either individually or in the aggregate, could have a material adverse effect on the Company’s financial position or results of operations; however, litigation is subject to inherent uncertainties.

Under the Company’s leases, tenants are typically obligated to indemnify the Company from and against all liabilities, costs, and expenses imposed upon or asserted against it as owner of the properties due to certain matters relating to the operation of the properties by the tenant.