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Capital Structure - Additional Information (Details) |  |  |  | 12 Months Ended | 48 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
May 18, 2020 USD ($) | Feb. 15, 2018 USD ($) director registration member vote $ / shares shares | Feb. 04, 2016 USD ($) | Dec. 31, 2020 USD ($) vote $ / shares shares | Dec. 31, 2018 USD ($) shares | Dec. 31, 2016 USD ($) shares | Dec. 31, 2020 USD ($) $ / shares shares | Aug. 19, 2020 USD ($) | Dec. 31, 2019 $ / shares shares
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Capital stock authorized (in shares) | shares |  |  |  | 110,000,000 |  |  | 110,000,000 |  |
Capital stock, par value (in dollars per share) | $ / shares |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  |
Common stock, shares authorized (in shares) | shares |  |  |  | 100,000,000 |  |  | 100,000,000 |  | 100,000,000
Preferred stock, shares authorized (in shares) | shares |  |  |  | 10,000,000 |  |  | 10,000,000 |  | 10,000,000
Aggregate amount of offering |  |  |  |  |  |  |  | $ 250,000,000.0 |
Dividends |  |  |  | $ 0 |  |  |  |  |
Stock repurchased during period, value |  |  |  |  | $ 44,830,000 |  |  |  |
Retirement of treasury stock (in shares) | shares |  |  |  |  | 3,900,000 |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  | 250,000 |  |  | 250,000 |  | 217,000
Preferred stock, par value (in dollars per share) | $ / shares |  |  |  | $ 0.0001 |  |  | $ 0.0001 |  | $ 0.0001
Preferred stock, shares outstanding (in shares) | shares |  |  |  | 250,000 |  |  | 250,000 |  | 217,000
Dividend rate, percentage |  | 14.50% |  |  |  |  |  |  |
Convertible preferred stock, shares to be issued upon conversion (in shares) | shares |  | 55.5556 |  |  |  |  |  |  |
Convertible preferred stock, conversion price per share (in dollars per share) | $ / shares |  | $ 18.00 |  |  |  |  |  |  |
Number of elected directors | director |  | 4 |  |  |  |  |  |  |
Number of board of director members | director |  | 10 |  |  |  |  |  |  |
Number of board of director members elected by preferred stock holders | director |  | 2 |  |  |  |  |  |  |
Number of board of directors agreed upon to be elected meeting independence criteria | director |  | 4 |  |  |  |  |  |  |
Number of board of directors elected meeting independence criteria | director |  | 2 |  |  |  |  |  |  |
Minimum number of board of director members that preferred stock holders can appoint pursuant to certification | director |  | 1 |  |  |  |  |  |  |
Maximum ownership threshold allowed for director election rights, percent |  | 30.00% |  |  |  |  |  |  |
Demand registrations allowed under agreement | registration |  | 3 |  |  |  |  |  |  |
Demand registrations allowed under agreement annually | registration |  | 2 |  |  |  |  |  |  |
Demand registration, minimum percentage of shares |  | 10.00% |  |  |  |  |  |  |
Chief Executive Officer |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of elected directors | director |  | 1 |  |  |  |  |  |  |
Board of Directors Chairman |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of elected directors | director |  | 1 |  |  |  |  |  |  |
Ten Percent or Greater Ownership |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of elected directors | member |  | 2 |  |  |  |  |  |  |
Preferred stock, ownership percentage |  | 10.00% |  |  |  |  |  |  |
Greater than Five and Less than Ten Percent Ownership |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of elected directors | member |  | 1 |  |  |  |  |  |  |
Intralinks Holdings, Inc. |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Payment of reimbursement fees |  | $ 5,000,000.0 |  |  |  |  |  |  |
Silver Private Holdings I, LLC |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of shares repurchased under program (in shares) | shares |  | 5,994,667 |  | 5,994,667 |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  | 185,000 |  |  |  |  |  |  |
Preferred stock, par value (in dollars per share) | $ / shares |  | $ 0.0001 |  |  |  |  |  |  |
Preferred stock, liquidation preference (in dollars per share) | $ / shares |  | $ 1,000 |  |  |  |  |  |  |
Consideration received on transaction |  | $ 97,700,000 |  |  |  |  |  |  |
Fair value, approval threshold |  | 10,000,000.0 |  |  |  |  |  |  |
Fair market value of transaction, individual |  | 5,000,000.0 |  |  |  |  |  |  |
Fair market value of transaction, aggregate |  | 10,000,000.0 |  |  |  |  |  |  |
Capital expenditure threshold |  | $ 25,000,000.0 |  |  |  |  |  |  |
Percentage ownership after conversion |  | 19.90% |  |  |  |  |  |  |
Voting percentage threshold of ownership |  | 19.99% |  |  |  |  |  |  |
Minimum number of board of director members that preferred stock holders can appoint pursuant to certification | director |  | 2 |  |  |  |  |  |  |
Siris LLC |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Advisory services, fee payable | $ 110,000 |  |  |  |  |  |  |  |
Increase in advisory services, fee payable | $ 10,000 |  |  |  |  |  |  |  |
Advisory services fee payable, percentage | 20.00% |  |  |  |  |  |  |  |
Minimum | Greater than Five and Less than Ten Percent Ownership |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Preferred stock, ownership percentage |  | 5.00% |  |  |  |  |  |  |
Maximum | Greater than Five and Less than Ten Percent Ownership |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Preferred stock, ownership percentage |  | 10.00% |  |  |  |  |  |  |
Share Repurchase Program2016 |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Stock repurchase program authorized amount |  |  | $ 100,000,000.0 |  |  |  |  |  |
Number of shares repurchased under program (in shares) | shares |  |  |  |  |  | 1,300,000 | 0 |  |
Stock repurchased during period, value |  |  |  |  |  | $ 40,000,000.0 |  |  |
Share Repurchase Program2016 | Minimum |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Stock repurchase program, period in force |  |  | 12 months |  |  |  |  |  |
Share Repurchase Program2016 | Maximum |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Stock repurchase program, period in force |  |  | 18 months |  |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of votes per share (vote) | vote |  |  |  | 1 |  |  |  |  |
Series A Preferred Stock |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of votes per share (vote) | vote |  | 1 |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  | 185,000 |  |  |  |  |  |  |
Preferred stock, shares outstanding (in shares) | shares |  |  |  | 250,432 |  |  | 250,432 |  |
Preferred stock, dividends (in shares) | shares |  |  |  | 65,432 |  |  |  |  |
Preferred stock, redemption period |  | 30 months |  |  |  |  |  |  |
Preferred stock, liquidation preference |  |  |  | $ 243,100,000 |  |  | $ 243,100,000 |  |
Preferred stock, redemption amount |  |  |  | $ 243,100,000 |  |  | $ 243,100,000 |  |

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