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Consolidated Statements of Redeemable Convertible Preferred Stock and Equity (Deficit) - USD ($) $ in Thousands | Total | Astra Zeneca [Member] | FibroGen Europe [Member] | Senior Preferred Stock [Member] | Senior Preferred Stock [Member] Astra Zeneca [Member] | Senior Preferred Stock [Member] FibroGen Europe [Member] | Junior Preferred Stock [Member] | Junior Preferred Stock [Member] Astra Zeneca [Member] | Junior Preferred Stock [Member] FibroGen Europe [Member] | Common Stock [Member] | Common Stock [Member] Astra Zeneca [Member] | Common Stock [Member] FibroGen Europe [Member] | Additional Paid-in Capital [Member] | Additional Paid-in Capital [Member] Astra Zeneca [Member] | Additional Paid-in Capital [Member] FibroGen Europe [Member] | Accumulated Other Comprehensive Loss [Member] | Accumulated Other Comprehensive Loss [Member] Astra Zeneca [Member] | Accumulated Other Comprehensive Loss [Member] FibroGen Europe [Member] | Accumulated Deficit [Member] | Accumulated Deficit [Member] Astra Zeneca [Member] | Accumulated Deficit [Member] FibroGen Europe [Member] | Noncontrolling Interest [Member] | Noncontrolling Interest [Member] Astra Zeneca [Member] | Noncontrolling Interest [Member] FibroGen Europe [Member]
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Balance at Dec. 31, 2012 | $ (46,252) |  |  | $ 168,436 |  |  | $ 136,313 |  |  | $ 132 |  |  | $ 37,606 |  |  | $ (167) |  |  | $ (247,836) |  |  | $ 27,700 |  |
Balance, Shares at Dec. 31, 2012 |  |  |  | 38,340,182 |  |  | 46,460,057 |  |  | 13,167,138 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss | (14,943) |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 0 |  |  | 0 |  |  | (14,943) |  |  | 0 |  |
Change in unrealized loss on investments | (2,676) |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | (2,676) |  |  | 0 |  |  | 0 |  |
Foreign currency translation adjustments | (665) |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | (665) |  |  | 0 |  |  | 0 |  |
Issuance of Series A Preferred to non-controlling interests | 175 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 175 |  |
Stock options exercised | 84 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 84 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Stock options exercised , Shares |  |  |  | 0 |  |  | 0 |  |  | 34,126 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation | 3,444 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 3,444 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Balance at Dec. 31, 2013 | (60,833) |  |  | $ 168,436 |  |  | $ 136,313 |  |  | $ 132 |  |  | 41,134 |  |  | (3,508) |  |  | (262,779) |  |  | 27,875 |  |
Balance, Shares at Dec. 31, 2013 |  |  |  | 38,340,182 |  |  | 46,460,057 |  |  | 13,201,264 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss | (59,504) |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 0 |  |  | 0 |  |  | (59,504) |  |  | 0 |  |
Change in unrealized loss on investments | (1,723) |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | (1,723) |  |  | 0 |  |  | 0 |  |
Foreign currency translation adjustments | 2,082 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 2,082 |  |  | 0 |  |  | 0 |  |
Stock options exercised | 1,694 |  |  | $ 0 |  |  | $ 0 |  |  | $ 5 |  |  | 1,689 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Stock options exercised , Shares |  |  |  | 0 |  |  | 0 |  |  | 539,971 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation | 18,698 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 18,698 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Balance at Dec. 31, 2014 | 240,676 |  |  | $ 0 |  |  | $ 0 |  |  | $ 590 |  |  | 546,247 |  |  | (3,149) |  |  | (322,283) |  |  | 19,271 |  |
Balance, Shares at Dec. 31, 2014 |  |  |  | 0 |  |  | 0 |  |  | 59,046,296 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion of preferred stock to common stock | $ 168,436 |  | $ 0 |  |  | $ 0 |  |  | $ 0 | $ 339 |  | $ 10 | $ 304,410 |  | $ 8,594 | $ 0 |  | $ 0 | $ 0 |  | $ 0 | $ 0 |  |
Conversion of preferred stock to common stock |  |  |  | $ (168,436) |  |  | $ (136,313) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (8,604)
Conversion of preferred stock to common stock, shares |  |  |  |  |  | 0 |  |  | 0 | 33,919,954 |  | 958,996 |  |  |  |  |  |  |  |  |  |  |  |
Conversion of preferred stock to common stock, shares | 0 |  |  | (38,340,182) |  |  | (46,460,057) |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Initial Public Offering, net of underwriting discounts, commission and issuance costs | $ 151,826 |  |  | $ 0 |  |  | $ 0 |  |  | $ 93 |  |  | $ 151,733 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |
Initial Public Offering, net of underwriting discounts, commission and issuance costs, shares |  |  |  | 0 |  |  | 0 |  |  | 9,315,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Astra Zeneca private placement |  | $ 20,000 |  |  | $ 0 |  |  | $ 0 |  |  | $ 11 |  |  | $ 19,989 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |
Astra Zeneca private placement, Shares |  |  |  |  | 0 |  |  | 0 |  |  | 1,111,111 |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss | (85,779) |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 0 |  |  | 0 |  |  | (85,779) |  |  | 0 |  |
Change in unrealized loss on investments | (164) |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | (164) |  |  | 0 |  |  | 0 |  |
Foreign currency translation adjustments | 1,662 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 1,662 |  |  | 0 |  |  | 0 |  |
Stock options exercised | 10,112 |  |  | $ 0 |  |  | $ 0 |  |  | $ 24 |  |  | 10,088 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Stock options exercised , Shares |  |  |  | 0 |  |  | 0 |  |  | 2,361,633 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation | 27,681 |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | 27,681 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Balance at Dec. 31, 2015 | 196,825 |  |  | $ 0 |  |  | $ 0 |  |  | $ 620 |  |  | 586,647 |  |  | (1,651) |  |  | (408,062) |  |  | 19,271 |  |
Balance, Shares at Dec. 31, 2015 |  |  |  | 0 |  |  | 0 |  |  | 61,985,079 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued upon vesting of restricted stock units and purchases made under the employee stock purchase plan, shares |  |  |  | 0 |  |  | 0 |  |  | 456,355 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued upon vesting of restricted stock units and purchases made under the employee stock purchase plan | 2,595 |  |  | $ 0 |  |  | $ 0 |  |  | $ 5 |  |  | 2,590 |  |  | 0 |  |  | 0 |  |  | 0 |  |
True up of issuance costs related to initial public offering and common stock sold by FibroGen Europe | 42 |  |  | 0 |  |  | 0 |  |  | 0 |  |  | 42 |  |  | 0 |  |  | 0 |  |  | 0 |  |
Warrants exercised | $ 0 |  |  | $ 0 |  |  | $ 0 |  |  | $ 1 |  |  | $ (1) |  |  | $ 0 |  |  | $ 0 |  |  | $ 0 |  |
Warrants exercised, Shares |  |  |  |  |  |  |  |  |  | 120,795 |  |  |  |  |  |  |  |  |  |  |  |  |  |

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