Significant Transactions During the Nine Months Ended September 30, 2019 and Subsequent Events	9 Months Ended
Sep. 30, 2019
Business Combinations [Abstract]
Significant Transactions During the Nine Months Ended September 30, 2019 and Subsequent Events	Significant Transactions During The Nine Months Ended September 30, 2019 and Subsequent Events Significant Transactions Acquisitions In March 2019, the Company acquired its joint venture partner’s 45.0% membership interest in One South Market, a multifamily community located in San Jose, CA, for total consideration of $80.6 million. Concurrent with the closing of the acquisition, $86.0 million in mortgage debt was repaid. As a result of this acquisition, the Company realized a gain on remeasurement of co-investment of $31.5 million upon consolidation. Furthermore, the Company recognized $0.8 million in promote income as a result of the transaction, which is included in equity income from co-investments on the condensed consolidated statements of income and comprehensive income. In June 2019, the Company acquired Brio, a 300 unit apartment home community located in Walnut Creek, CA. The Company issued DownREIT limited partnership units to an affiliate of Marcus & Millichap Company, based on a contract price of $164.9 million. The property was encumbered by $98.7 million of mortgage debt which was assumed by the Company at the time of acquisition. As a result of this transaction, the Company consolidated the property, based on a VIE analysis performed by the Company. See Note 6, Related Party Transactions, for additional details. In August 2019, Wesco V, LLC ("Wesco V"), one of the Company's joint ventures, acquired The Courtyards at 65th Street, a 331 unit apartment home community located in Emeryville, CA, for a total contract price of $178.0 million. The property was encumbered by an $89.0 million related party bridge loan from the Company, with an interest rate of LIBOR plus 1.30% and a maturity date of December 2019. See Note 6, Related Party Transactions, for additional details. In August 2019, BEX IV, LLC ("BEX IV"), one of the Company's joint ventures, acquired 777 Hamilton, a 195 unit apartment home community located in Menlo Park, CA, for a total contract price of $148.0 million. The property is encumbered by a $44.4 million related party bridge loan from the Company, with an interest rate of 3.25% and a maturity date of November 2019. See "Co-investments" section below for further details related to the creation of BEX IV. See Note 6, Related Party Transactions, for additional details. In September 2019, the Company acquired Township, a 132 unit apartment home community in Redwood City, CA, for a total contract price of $88.7 million. The property was encumbered by $44.3 million of mortgage debt, which was assumed by the Company at the time of acquisition. Dispositions In May 2019, the Company sold its 50.0% ownership interest in a co-investment that held land located in Oakland, CA for $6.1 million, resulting in a gain of $0.9 million within equity income from co-investments. Co-Investments Joint Ventures In August 2019, the Company formed a new joint venture entity, BEX IV, with an institutional partner. The Company has a 50.1% ownership interest in the joint venture and an initial equity commitment of $52.2 million. The joint venture is unconsolidated for financial reporting purposes. Preferred Equity Investments In February 2019, the Company funded a $24.5 million related party preferred equity investment in a multifamily development community located in Mountain View, CA. The investment has an initial preferred return of 11.0% and is scheduled to mature in February 2024. See Note 6, Related Party Transactions, for additional details. In February 2019, the Company received cash of $10.9 million, including an early redemption fee of $0.1 million, for the full redemption of a related party preferred equity investment in a joint venture that holds property in San Jose, CA. See Note 6, Related Party Transactions, for additional details. In March 2019, the Company made a commitment to fund a $36.0 million preferred equity commitment in a multifamily development community located in Irvine, CA. The investment has an initial preferred return of 10.15% and is scheduled to mature in July 2022. As of September 30, 2019, the Company had funded $21.6 million of this commitment. The remaining committed amount is expected to be funded by the end of the year. In April 2019, the Company received cash of $16.3 million, including an early redemption fee of $0.7 million, for the full redemption of a preferred equity investment in a joint venture that holds property in Santa Ana, CA. In April 2019, the Company made a commitment to fund a $36.8 million preferred equity investment in a multifamily development community located in Oakland, CA. The investment has an initial preferred return of 10.25% and is scheduled to mature in April 2023. As of September 30, 2019, the Company had funded $15.0 million of this commitment. The remaining committed amount is expected to be funded by the end of the year. In April 2019, the Company made a commitment to fund a $11.8 million preferred equity investment in a multifamily development community located in Oakland, CA. The investment has an initial preferred return of 11.0% and is scheduled to mature in April 2023. As of September 30, 2019, the Company had funded $5.5 million of this commitment. The remaining committed amount is expected to be funded by the end of the year. In September 2019, the Company received cash of $14.8 million, including an early redemption fee of $0.3 million, for the full redemption of a preferred equity investment in a property located in Redmond, WA. In September 2019, the Company received cash of $16.3 million, including an early redemption fee of $1.4 million, for the full redemption of a preferred equity investment in a property located in Seattle, WA. Common Stock In January 2019, the Company repurchased and retired 234,061 shares totaling $57.0 million, including commissions. In February 2019, the board of directors approved the replenishment of the stock repurchase plan such that, as of such date, the Company had $250.0 million of purchase authority remaining under the replenished plan. As of September 30, 2019, the Company had $250.0 million of purchase authority remaining under the stock repurchase plan. During the nine months ended September 30, 2019, the Company issued 228,271 shares of common stock through its equity distribution program at an average price of $321.56 per share for proceeds of $73.4 million. There were no such sales during the nine months ended September 30, 2018. Senior Unsecured Debt In February 2019, the Operating Partnership issued $350.0 million of senior unsecured notes due on March 1, 2029, with a coupon rate of 4.000% (the "2029 Notes"), which are payable on March 1 and September 1 of each year, beginning on September 1, 2019. The 2029 Notes were offered to investors at a price of 99.188% of the principal amount thereof. The 2029 Notes are general unsecured senior obligations of the Operating Partnership, rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership and are unconditionally guaranteed by the Company. In March 2019, the Operating Partnership issued an additional $150.0 million of the 2029 Notes at a price of 100.717% of the principal amount thereof. These additional notes have substantially identical terms as the 2029 Notes issued in February 2019. The Company used the net proceeds of these offerings to repay indebtedness under its unsecured lines of credit and for other general corporate and working capital purposes. In August 2019, the Operating Partnership issued $400.0 million of senior unsecured notes due on January 15, 2030, with a coupon rate of 3.000% (the "2030 Notes"), which are payable on January 15 and July 15 of each year, beginning on January 15, 2020. The 2030 Notes were offered to investors at a price of 98.632% of the principal amount thereof. The 2030 Notes are general unsecured senior obligations of the Operating Partnership, rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership and are unconditionally guaranteed by the Company. The Company used the net proceeds of this offering to prepay, with no prepayment penalties, certain secured indebtedness under outstanding mortgage notes, to repay indebtedness under its unsecured lines of credit and for other general corporate and working capital purposes. Mortgage Notes Payable In January 2019, the Company repaid $290.0 million in secured mortgage notes payable with a coupon rate of 5.57% and a stated maturity date of May 2019. The Company realized a gain on early extinguishment of debt of $1.4 million. In September 2019, the Company repaid $289.1 million in secured mortgage notes payable with a coupon rate of 5.69% and a stated maturity date of September 2020. The Company realized a gain on early extinguishment of debt of $5.5 million. Subsequent Events In October 2019, the Operating Partnership issued an additional $150.0 million of the 2030 Notes at a price of 101.685% of the principal amount thereof. The notes were issued as additional notes under the 2030 Notes indenture and have substantially identical terms as the 2030 Notes issued in August 2019. In October 2019, the Company received cash of $15.8 million, including an early redemption fee of $0.2 million, for the full redemption of a preferred equity investment in a property located in San Jose, CA.

In March 2019, the Company acquired its joint venture partner’s 45.0% membership interest in One South Market, a multifamily community located in San Jose, CA, for total consideration of $80.6 million. Concurrent with the closing of the acquisition, $86.0 million in mortgage debt was repaid. As a result of this acquisition, the Company realized a gain on remeasurement of co-investment of $31.5 million upon consolidation. Furthermore, the Company recognized $0.8 million in promote income as a result of the transaction, which is included in equity income from co-investments on the condensed consolidated statements of income and comprehensive income.

In June 2019, the Company acquired Brio, a 300 unit apartment home community located in Walnut Creek, CA. The Company issued DownREIT limited partnership units to an affiliate of Marcus & Millichap Company, based on a contract price of $164.9 million. The property was encumbered by $98.7 million of mortgage debt which was assumed by the Company at the time of acquisition. As a result of this transaction, the Company consolidated the property, based on a VIE analysis performed by the Company. See Note 6, Related Party Transactions, for additional details.

In August 2019, Wesco V, LLC ("Wesco V"), one of the Company's joint ventures, acquired The Courtyards at 65th Street, a 331 unit apartment home community located in Emeryville, CA, for a total contract price of $178.0 million. The property was encumbered by an $89.0 million related party bridge loan from the Company, with an interest rate of LIBOR plus 1.30% and a maturity date of December 2019. See Note 6, Related Party Transactions, for additional details.

In August 2019, BEX IV, LLC ("BEX IV"), one of the Company's joint ventures, acquired 777 Hamilton, a 195 unit apartment home community located in Menlo Park, CA, for a total contract price of $148.0 million. The property is encumbered by a $44.4 million related party bridge loan from the Company, with an interest rate of 3.25% and a maturity date of November 2019. See "Co-investments" section below for further details related to the creation of BEX IV. See Note 6, Related Party Transactions, for additional details.

In September 2019, the Company acquired Township, a 132 unit apartment home community in Redwood City, CA, for a total contract price of $88.7 million. The property was encumbered by $44.3 million of mortgage debt, which was assumed by the Company at the time of acquisition.

In May 2019, the Company sold its 50.0% ownership interest in a co-investment that held land located in Oakland, CA for $6.1 million, resulting in a gain of $0.9 million within equity income from co-investments.

In August 2019, the Company formed a new joint venture entity, BEX IV, with an institutional partner. The Company has a 50.1% ownership interest in the joint venture and an initial equity commitment of $52.2 million. The joint venture is unconsolidated for financial reporting purposes.

In February 2019, the Company funded a $24.5 million related party preferred equity investment in a multifamily development community located in Mountain View, CA. The investment has an initial preferred return of 11.0% and is scheduled to mature in February 2024. See Note 6, Related Party Transactions, for additional details.

In February 2019, the Company received cash of $10.9 million, including an early redemption fee of $0.1 million, for the full redemption of a related party preferred equity investment in a joint venture that holds property in San Jose, CA. See Note 6, Related Party Transactions, for additional details.

In March 2019, the Company made a commitment to fund a $36.0 million preferred equity commitment in a multifamily development community located in Irvine, CA. The investment has an initial preferred return of 10.15% and is scheduled to mature in July 2022. As of September 30, 2019, the Company had funded $21.6 million of this commitment. The remaining committed amount is expected to be funded by the end of the year.

In April 2019, the Company received cash of $16.3 million, including an early redemption fee of $0.7 million, for the full redemption of a preferred equity investment in a joint venture that holds property in Santa Ana, CA.

In April 2019, the Company made a commitment to fund a $36.8 million preferred equity investment in a multifamily development community located in Oakland, CA. The investment has an initial preferred return of 10.25% and is scheduled to mature in April 2023. As of September 30, 2019, the Company had funded $15.0 million of this commitment. The remaining committed amount is expected to be funded by the end of the year.

In April 2019, the Company made a commitment to fund a $11.8 million preferred equity investment in a multifamily development community located in Oakland, CA. The investment has an initial preferred return of 11.0% and is scheduled to mature in April 2023. As of September 30, 2019, the Company had funded $5.5 million of this commitment. The remaining committed amount is expected to be funded by the end of the year.

In September 2019, the Company received cash of $14.8 million, including an early redemption fee of $0.3 million, for the full redemption of a preferred equity investment in a property located in Redmond, WA.

In September 2019, the Company received cash of $16.3 million, including an early redemption fee of $1.4 million, for the full redemption of a preferred equity investment in a property located in Seattle, WA.

In January 2019, the Company repurchased and retired 234,061 shares totaling $57.0 million, including commissions. In February 2019, the board of directors approved the replenishment of the stock repurchase plan such that, as of such date, the Company had $250.0 million of purchase authority remaining under the replenished plan. As of September 30, 2019, the Company had $250.0 million of purchase authority remaining under the stock repurchase plan.

During the nine months ended September 30, 2019, the Company issued 228,271 shares of common stock through its equity distribution program at an average price of $321.56 per share for proceeds of $73.4 million. There were no such sales during the nine months ended September 30, 2018.

In February 2019, the Operating Partnership issued $350.0 million of senior unsecured notes due on March 1, 2029, with a coupon rate of 4.000% (the "2029 Notes"), which are payable on March 1 and September 1 of each year, beginning on September 1, 2019. The 2029 Notes were offered to investors at a price of 99.188% of the principal amount thereof. The 2029 Notes are general unsecured senior obligations of the Operating Partnership, rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership and are unconditionally guaranteed by the Company. In March 2019, the Operating Partnership issued an additional $150.0 million of the 2029 Notes at a price of 100.717% of the principal amount thereof. These additional notes have substantially identical terms as the 2029 Notes issued in February 2019. The Company used the net proceeds of these offerings to repay indebtedness under its unsecured lines of credit and for other general corporate and working capital purposes.

In August 2019, the Operating Partnership issued $400.0 million of senior unsecured notes due on January 15, 2030, with a coupon rate of 3.000% (the "2030 Notes"), which are payable on January 15 and July 15 of each year, beginning on January 15, 2020. The 2030 Notes were offered to investors at a price of 98.632% of the principal amount thereof. The 2030 Notes are general unsecured senior obligations of the Operating Partnership, rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership and are unconditionally guaranteed by the Company. The Company used the net proceeds of this offering to prepay, with no prepayment penalties, certain secured indebtedness under outstanding mortgage notes, to repay indebtedness under its unsecured lines of credit and for other general corporate and working capital purposes.

In January 2019, the Company repaid $290.0 million in secured mortgage notes payable with a coupon rate of 5.57% and a stated maturity date of May 2019. The Company realized a gain on early extinguishment of debt of $1.4 million.

In September 2019, the Company repaid $289.1 million in secured mortgage notes payable with a coupon rate of 5.69% and a stated maturity date of September 2020. The Company realized a gain on early extinguishment of debt of $5.5 million.

In October 2019, the Operating Partnership issued an additional $150.0 million of the 2030 Notes at a price of 101.685% of the principal amount thereof. The notes were issued as additional notes under the 2030 Notes indenture and have substantially identical terms as the 2030 Notes issued in August 2019.