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Noncontrolling Interests on the Company's Consolidated Financial Statements - Additional Information (Details) $ / shares in Units, $ in Thousands | 3 Months Ended | 6 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Sep. 30, 2021 USD ($) shares $ / shares | Sep. 30, 2020 USD ($) | Jun. 30, 2020 USD ($) | Sep. 30, 2021 USD ($) shares $ / shares | Sep. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) shares
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Redemption and conversion of common units | $ |  |  | $ (1,536) |  |  |
Net income | $ | $ 22,683 | $ 802 |  | $ 28,489 | $ 10,073 |
Accumulated other comprehensive loss allocation | $ | $ 415 | 317 |  | $ 229 | (2,664) |
SL Green Operating Partnership |  |  |  |  |  |
Organization |  |  |  |  |  |
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares) | 3,888,034 |  |  | 3,888,034 |  | 3,938,823
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | 3,888,034 |  |  | 3,888,034 |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Redemption and conversion of common units | $ |  |  | (1,536) |  |  |
Accumulated other comprehensive loss allocation | $ | $ 415 | $ 317 |  | $ 229 | (2,664) |
SL Green Operating Partnership | 3.50% Series A |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 3.50% |  |
Preferred units, shares authorized (in shares) | 109,161 |  |  | 109,161 |  |
Number of preferred units issued (in shares) | 109,161 |  |  | 109,161 |  |
Number of Units Outstanding (in shares) | 109,161 |  |  | 109,161 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 35.0000 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 1,000 |  |  | 1,000 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
Number of company common stock issued on conversion of Series B preferred units |  |  |  | 6.71348 |  |
SL Green Operating Partnership | Series F |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 700.00% |  |
Preferred units, shares authorized (in shares) | 60 |  |  | 60 |  |
Number of preferred units issued (in shares) | 60 |  |  | 60 |  |
Number of Units Outstanding (in shares) | 60 |  |  | 60 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 70.0000 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 1,000 |  |  | 1,000 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 29.12 |  |  | $ 29.12 |  |
SL Green Operating Partnership | 4.50% Series G |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 450.00% |  |
Preferred units, shares authorized (in shares) | 1,902,000 |  |  | 1,902,000 |  |
Number of preferred units issued (in shares) | 1,902,000 |  |  | 1,902,000 |  |
Number of Units Outstanding (in shares) | 718,697 |  |  | 718,697 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 1.1250 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 88.50 |  |  | $ 88.50 |  |
Number of company common stock issue on redemption of operation partnership common units |  |  |  | 1 |  |
SL Green Operating Partnership | Series K |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 350.00% |  |
Preferred units, shares authorized (in shares) | 700,000 |  |  | 700,000 |  |
Number of preferred units issued (in shares) | 563,954 |  |  | 563,954 |  |
Number of Units Outstanding (in shares) | 341,677 |  |  | 341,677 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 0.8750 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 134.67 |  |  | $ 134.67 |  |
SL Green Operating Partnership | Series L |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 400.00% |  |
Preferred units, shares authorized (in shares) | 500,000 |  |  | 500,000 |  |
Number of preferred units issued (in shares) | 378,634 |  |  | 378,634 |  |
Number of Units Outstanding (in shares) | 372,634 |  |  | 372,634 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 1.0000 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
SL Green Operating Partnership | Series M |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 375.00% |  |
Preferred units, shares authorized (in shares) | 1,600,000 |  |  | 1,600,000 |  |
Number of preferred units issued (in shares) | 1,600,000 |  |  | 1,600,000 |  |
Number of Units Outstanding (in shares) | 96,357 |  |  | 96,357 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 0.9375 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
SL Green Operating Partnership | Series P |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 400.00% |  |
Preferred units, shares authorized (in shares) | 200,000 |  |  | 200,000 |  |
Number of preferred units issued (in shares) | 200,000 |  |  | 200,000 |  |
Number of Units Outstanding (in shares) | 200,000 |  |  | 200,000 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 1.0000 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
SL Green Operating Partnership | Series Q |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 350.00% |  |
Preferred units, shares authorized (in shares) | 268,000 |  |  | 268,000 |  |
Number of preferred units issued (in shares) | 268,000 |  |  | 268,000 |  |
Number of Units Outstanding (in shares) | 268,000 |  |  | 268,000 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 0.8750 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 148.95 |  |  | $ 148.95 |  |
SL Green Operating Partnership | Series R |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 350.00% |  |
Preferred units, shares authorized (in shares) | 400,000 |  |  | 400,000 |  |
Number of preferred units issued (in shares) | 400,000 |  |  | 400,000 |  |
Number of Units Outstanding (in shares) | 400,000 |  |  | 400,000 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 0.8750 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 154.89 |  |  | $ 154.89 |  |
SL Green Operating Partnership | Series S |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 400.00% |  |
Preferred units, shares authorized (in shares) | 1,077,280 |  |  | 1,077,280 |  |
Number of preferred units issued (in shares) | 1,077,280 |  |  | 1,077,280 |  |
Number of Units Outstanding (in shares) | 1,077,280 |  |  | 1,077,280 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 1.0000 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
SL Green Operating Partnership | Series V |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Dividend rate preferred units (as a percent) |  |  |  | 350.00% |  |
Preferred units, shares authorized (in shares) | 40,000 |  |  | 40,000 |  |
Number of preferred units issued (in shares) | 40,000 |  |  | 40,000 |  |
Number of Units Outstanding (in shares) | 40,000 |  |  | 40,000 |  |
Annual dividends on preferred units (in dollars per share) | $ / shares |  |  |  | $ 0.8750 |  |
Liquidation preference of preferred units (in dollars per share) | $ / shares | $ 25.00 |  |  | 25.00 |  |
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares | $ 0 |  |  | $ 0 |  |
SL Green Operating Partnership | Series W |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Preferred units, shares authorized (in shares) | 1 |  |  | 1 |  |
Number of preferred units issued (in shares) | 1 |  |  | 1 |  |
Number of Units Outstanding (in shares) | 1 |  |  | 1 |  |
Preferred stock, dividend, multiplier per common unit distribution |  |  |  | 1,350 |  |
Partnership Interest |  |  |  |  |  |
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership |  |  |  |  |  |
Balance at beginning of period | $ |  |  | $ 409,862 | $ 358,262 | $ 409,862 | $ 409,862
Distributions | $ |  |  |  | (11,882) |  | (12,652)
Issuance of common units | $ |  |  |  | 11,910 |  | 12,018
Redemption and conversion of common units | $ |  |  |  | (41,516) |  | (36,085)
Net income | $ |  |  |  | 28,489 |  | 20,016
Accumulated other comprehensive loss allocation | $ |  |  |  | 229 |  | (2,299)
Fair value adjustment | $ |  |  |  | 17,245 |  | (32,598)
Balance at end of period | $ | $ 362,737 |  |  | $ 362,737 |  | $ 358,262
Operating Partnership | SL Green Operating Partnership |  |  |  |  |  |
Organization |  |  |  |  |  |
Noncontrolling interest in the operating partnership (as a percent) | 5.50% |  |  | 5.50% |  | 5.44%

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