Noncontrolling Interests on the Company's Consolidated Financial Statements	12 Months Ended
Dec. 31, 2017
Noncontrolling Interest [Abstract]
Noncontrolling Interests on the Company's Consolidated Financial Statements	Noncontrolling Interests on the Company’s Consolidated Financial Statements Common Units of the Operating Partnership The Company owned a 97.9% and 97.5% common general partnership interest in the Operating Partnership as of December 31, 2017 and 2016, respectively. The remaining 2.1% and 2.5% common limited partnership interest as of December 31, 2017 and 2016, respectively, was owned by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units. There were 2,077,193 and 2,381,543 common units outstanding held by these investors, executive officers and directors as of December 31, 2017 and 2016, respectively. The decrease in the common units from December 31, 2016 to December 31, 2017 was attributable to 304,350 common unit redemptions. The noncontrolling common units may be redeemed by unitholders for cash. Except under certain circumstances, we, at our option, may satisfy the cash redemption obligation with shares of the Company’s common stock on a one-for-one basis. If satisfied in cash, the value for each noncontrolling common unit upon redemption is the amount equal to the average of the closing quoted price per share of the Company’s common stock, par value $0.01 per share, as reported on the NYSE for the ten trading days immediately preceding the applicable redemption date. The aggregate value upon redemption of the then-outstanding noncontrolling common units was $154.5 million and $174.9 million as of December 31, 2017 and 2016, respectively. This redemption value does not necessarily represent the amount that would be distributed with respect to each noncontrolling common unit in the event of our termination or liquidation. In the event of our termination or liquidation, it is expected in most cases that each common unit would be entitled to a liquidating distribution equal to the liquidating distribution payable in respect of each share of the Company’s common stock. Noncontrolling Interest in Consolidated Property Partnerships On August 30, 2016, the Operating Partnership entered into agreements with Norges Bank Real Estate Management (“NBREM”) whereby NBREM invested, through two REIT subsidiaries, in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. Based on a gross valuation of the two properties of approximately $1.2 billion, NBREM contributed a total of $452.9 million, for a 44% common equity interest in the companies, which was net of approximately $55.3 million of its proportionate share of the existing mortgage debt on 303 Second Street as of the transaction date. In November 2017, NBREM contributed $54.4 million to fund their proportionate share of the Company’s repayment of this mortgage debt. The transaction was structured with a staggered closing. On August 30, 2016, the first tranche of the transaction closed and NBREM contributed $191.4 million plus a working capital contribution of $2.1 million for a 44% common ownership interest in 100 First LLC. On November 30, 2016, the second tranche of the transaction closed and NBREM contributed $261.5 million, which was net of its proportionate share of the existing mortgage debt secured by the 303 Second Street property of approximately $55.3 million, plus a working capital contribution of $2.9 million for a 44% common ownership interest in 303 Second LLC. The transactions did not meet the criteria to qualify as sales of real estate because the Company continues to effectively control the properties and therefore continued to account for the 100 First Street and 303 Second Street office properties on a consolidated basis in its financial statements. At formation, the Company accounted for the transactions as equity transactions and recognized noncontrolling interests in its consolidated balance sheets totaling approximately $124.5 million, which was equal to 44% of the aggregate net asset value of 100 First LLC and 303 Second LLC immediately prior to the transactions (which was net of NBREM’s 44% share of the existing mortgage debt of $55.3 million) plus an additional $5.0 million working capital contribution made by NBREM. The amount of NBREM’s total contribution not recognized as noncontrolling interest, net of transaction costs, was approximately $329.0 million. This amount was not reflected as a gain on sale of operating properties in the Company’s consolidated statements of operations and instead was reflected as an increase in additional paid-in capital and partners’ capital in the Company’s and the Operating Partnership’s consolidated balance sheets, respectively. Transfers of less than 50% of an entity ownership interest are normally not subject to certain tax assessments in California and therefore the Company believes that the two tranches of the transaction do not meet the statutory requirements for such tax assessments. If the taxing authority attempted to assess such tax assessments on the transactions, the Company estimates it could incur additional taxes of up to $10.9 million and $18.0 million for the first and second tranches of the transaction, respectively, plus potential penalties and interest. In connection with the transaction, the Company provides customary property management, leasing and construction management services for both properties. 100 First Street is a 467,095 square foot office tower, and 303 Second Street is a 740,047 square foot office property, both located in the South of Market submarket in San Francisco, California. The noncontrolling interests in 100 First LLC and 303 Second LLC as of December 31, 2017 and 2016 were $175.4 million and $124.3 million, respectively, which is recognized in noncontrolling interests in consolidated property partnerships on the Company’s consolidated balance sheets. The remaining amount of noncontrolling interests in consolidated property partnerships represents the third party equity interest in Redwood LLC. This noncontrolling interest was $6.2 million and $6.4 million as of December 31, 2017 and 2016, respectively. Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements Consolidated Property Partnerships On August 30, 2016, the Operating Partnership entered into agreements with NBREM whereby NBREM invested, through two REIT subsidiaries, in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. Based on a gross valuation of the two properties of approximately $1.2 billion, NBREM contributed a total of $452.9 million for a 44% common equity interest in the companies, which is net of approximately $55.3 million of its proportionate share of the existing mortgage debt. In November 2017, the Company repaid the mortgage debt secured by the 303 Second Street office property. Prior to the repayment, NBREM contributed $54.4 million to fund their proportionate share of the repayment. Refer to Note 11 for additional information regarding these transactions.

Noncontrolling Interests on the Company’s Consolidated Financial Statements

Common Units of the Operating Partnership

The Company owned a 97.9% and 97.5% common general partnership interest in the Operating Partnership as of December 31, 2017 and 2016, respectively. The remaining 2.1% and 2.5% common limited partnership interest as of December 31, 2017 and 2016, respectively, was owned by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units. There were 2,077,193 and 2,381,543 common units outstanding held by these investors, executive officers and directors as of December 31, 2017 and 2016, respectively. The decrease in the common units from December 31, 2016 to December 31, 2017 was attributable to 304,350 common unit redemptions.

The noncontrolling common units may be redeemed by unitholders for cash. Except under certain circumstances, we, at our option, may satisfy the cash redemption obligation with shares of the Company’s common stock on a one-for-one basis. If satisfied in cash, the value for each noncontrolling common unit upon redemption is the amount equal to the average of the closing quoted price per share of the Company’s common stock, par value $0.01 per share, as reported on the NYSE for the ten trading days immediately preceding the applicable redemption date. The aggregate value upon redemption of the then-outstanding noncontrolling common units was $154.5 million and $174.9 million as of December 31, 2017 and 2016, respectively. This redemption value does not necessarily represent the amount that would be distributed with respect to each noncontrolling common unit in the event of our termination or liquidation. In the event of our termination or liquidation, it is expected in most cases that each common unit would be entitled to a liquidating distribution equal to the liquidating distribution payable in respect of each share of the Company’s common stock.

Noncontrolling Interest in Consolidated Property Partnerships

On August 30, 2016, the Operating Partnership entered into agreements with Norges Bank Real Estate Management (“NBREM”) whereby NBREM invested, through two REIT subsidiaries, in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. Based on a gross valuation of the two properties of approximately $1.2 billion, NBREM contributed a total of $452.9 million, for a 44% common equity interest in the companies, which was net of approximately $55.3 million of its proportionate share of the existing mortgage debt on 303 Second Street as of the transaction date. In November 2017, NBREM contributed $54.4 million to fund their proportionate share of the Company’s repayment of this mortgage debt.

The transaction was structured with a staggered closing. On August 30, 2016, the first tranche of the transaction closed and NBREM contributed $191.4 million plus a working capital contribution of $2.1 million for a 44% common ownership interest in 100 First LLC. On November 30, 2016, the second tranche of the transaction closed and NBREM contributed $261.5 million, which was net of its proportionate share of the existing mortgage debt secured by the 303 Second Street property of approximately $55.3 million, plus a working capital contribution of $2.9 million for a 44% common ownership interest in 303 Second LLC.

The transactions did not meet the criteria to qualify as sales of real estate because the Company continues to effectively control the properties and therefore continued to account for the 100 First Street and 303 Second Street office properties on a consolidated basis in its financial statements. At formation, the Company accounted for the transactions as equity transactions and recognized noncontrolling interests in its consolidated balance sheets totaling approximately $124.5 million, which was equal to 44% of the aggregate net asset value of 100 First LLC and 303 Second LLC immediately prior to the transactions (which was net of NBREM’s 44% share of the existing mortgage debt of $55.3 million) plus an additional $5.0 million working capital contribution made by NBREM. The amount of NBREM’s total contribution not recognized as noncontrolling interest, net of transaction costs, was approximately $329.0 million. This amount was not reflected as a gain on sale of operating properties in the Company’s consolidated statements of operations and instead was reflected as an increase in additional paid-in capital and partners’ capital in the Company’s and the Operating Partnership’s consolidated balance sheets, respectively. Transfers of less than 50% of an entity ownership interest are normally not subject to certain tax assessments in California and therefore the Company believes that the two tranches of the transaction do not meet the statutory requirements for such tax assessments. If the taxing authority attempted to assess such tax assessments on the transactions, the Company estimates it could incur additional taxes of up to $10.9 million and $18.0 million for the first and second tranches of the transaction, respectively, plus potential penalties and interest. In connection with the transaction, the Company provides customary property management, leasing and construction management services for both properties. 100 First Street is a 467,095 square foot office tower, and 303 Second Street is a 740,047 square foot office property, both located in the South of Market submarket in San Francisco, California.

The noncontrolling interests in 100 First LLC and 303 Second LLC as of December 31, 2017 and 2016 were $175.4 million and $124.3 million, respectively, which is recognized in noncontrolling interests in consolidated property partnerships on the Company’s consolidated balance sheets. The remaining amount of noncontrolling interests in consolidated property partnerships represents the third party equity interest in Redwood LLC. This noncontrolling interest was $6.2 million and $6.4 million as of December 31, 2017 and 2016, respectively.