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Equity Compensation Plans - Additional Information (Details) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
May 31, 2014 | Dec. 31, 2017 USD ($) $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Mar. 31, 2016 USD ($) executive | Dec. 31, 2015 $ / shares shares | Dec. 31, 2017 USD ($) tranche measurement_period $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Shares of common stock available for grant under Redwood's Incentive Plan (in shares) |  | 1,356,438 | 1,787,974 |  |  | 1,356,438 | 1,787,974 |
Unrecognized compensation cost | $ |  | $ 21,470 | $ 18,146 |  |  | $ 21,470 | $ 18,146 |
Equity compensation expense | $ |  |  |  |  |  | 10,141 | 9,093 | $ 11,921
Share-based compensation expense including restructuring | $ |  |  |  |  |  | $ 10,141 |  |
Number of shares purchased by employees (in shares) |  |  |  |  |  | 361,006 |  |
Performance Share Units (PSUs), 2017 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Grant date fair value assumptions, average closing stock price of common stock, measurement period (in days) |  |  |  |  |  | 60 days |  |
Restricted Stock |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Unrecognized compensation cost | $ |  | 3,000 |  |  |  | $ 3,000 |  |
Weighted average amortization period remaining for equity awards (in years) |  |  |  |  |  | 2 years |  |
Equity compensation expense | $ |  |  |  |  |  | $ 1,000 | $ 1,000 | $ 1,000
Number of stock awards granted (in shares) |  |  |  |  |  | 134,364 | 144,056 | 141,069
Number of stock awards forfeited (in shares) |  |  |  |  |  | 19,444 | 76,614 | 20,678
Number of stock awards vested (in shares) |  |  |  |  |  | 61,928 | 50,107 | 42,675
Deferred Stock Units |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Unrecognized compensation cost | $ |  | $ 13,000 |  |  |  | $ 13,000 |  |
Equity compensation expense | $ |  |  |  |  |  | $ 6,000 | $ 9,000 | $ 7,000
Unvested outstanding stock awards (in units) |  | 988,656 | 908,963 |  | 1,043,606 | 988,656 | 908,963 | 1,043,606
Weighted-average grant date fair value of stock awards (in dollars per unit) | $ / shares |  | $ 15.20 | $ 14.96 |  | $ 17.22 | $ 15.20 | $ 14.96 | $ 17.22
Share-based compensation expense including restructuring | $ |  |  |  | $ 3,000 |  |  |  |
Number of executives departing | executive |  |  |  | 2 |  |  |  |
Number of stock awards vested (in units) |  | 889,835 | 939,899 |  | 1,363,548 | 889,835 | 939,899 | 1,363,548
Number of stock awards granted (in shares) |  |  |  |  |  | 565,921 | 565,061 | 583,958
Number of stock awards forfeited (in shares) |  |  |  |  |  | 31,875 | 62,894 | 10,167
Performance Stock Units |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Unrecognized compensation cost | $ |  | $ 5,000 |  |  |  | $ 5,000 |  |
Equity compensation expense | $ |  |  |  |  |  | $ 2,000 | $ 3,000 | $ 3,000
Unvested outstanding stock awards (in units) |  | 704,270 | 642,879 |  |  | 704,270 | 642,879 |
Weighted-average grant date fair value of stock awards (in dollars per unit) | $ / shares |  | $ 11.17 | $ 13.24 |  | $ 9.46 | $ 11.17 | $ 13.24 | $ 9.46
Share-based compensation expense including restructuring | $ |  |  |  | $ 600 |  |  |  |
Number of executives departing | executive |  |  |  | 2 |  |  |  |
Number of stock awards granted (in shares) |  |  |  |  |  | 273,054 | 194,484 | 356,762
Number of stock awards forfeited (in shares) |  |  |  |  |  | 0 | 208,330 | 0
Performance Stock Units | Performance Share Units (PSUs), 2015 and 2017 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based compensation, vesting period (in years) |  |  |  |  |  | 3 years |  |
TSR performance period (in years) |  |  |  |  |  | 3 years |  |
Award vesting rights, total share return, percentage |  |  |  |  |  | 125.00% |  |
Performance Stock Units | Performance Share Units (PSUs), 2016 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based compensation, vesting period (in years) |  |  |  |  |  | 3 years |  |
TSR performance period (in years) |  |  |  |  |  | 2 years |  |
Performance shares, number of measurement periods | measurement_period |  |  |  |  |  | 4 |  |
Performance shares, number of vesting tranches | tranche |  |  |  |  |  | 4 |  |
Grant date fair value assumptions, average closing stock price of common stock, measurement period (in days) |  |  |  |  |  | 60 days |  |
Grant date fair value assumptions, volatility rate |  |  |  |  |  | 29.00% |  |
Grant date fair value assumptions, risk-free rate |  |  |  |  |  | 1.57% |  |
Grant date fair value assumptions, dividend yield |  |  |  |  |  | 0.00% |  |
Grant date fair value assumptions, dividend rate, risk-free rate, treasury rate measurement period (in years) |  |  |  |  |  | 3 years |  |
Performance Stock Units | Performance Share Units (PSUs), 2017 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
TSR performance period (in years) |  |  |  |  |  | 3 years |  |
Grant date fair value assumptions, volatility rate |  |  |  |  |  | 27.00% |  |
Grant date fair value assumptions, risk-free rate |  |  |  |  |  | 1.90% |  |
Grant date fair value assumptions, dividend yield |  |  |  |  |  | 0.00% |  |
Performance Stock Units | Performance Share Units (PSUs), 2015 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
TSR performance period (in years) |  |  |  |  |  | 3 years |  |
Grant date fair value assumptions, average closing stock price of common stock, measurement period (in days) |  |  |  |  |  | 40 days |  |
Grant date fair value assumptions, volatility rate |  |  |  |  |  | 26.00% |  |
Grant date fair value assumptions, risk-free rate |  |  |  |  |  | 1.35% |  |
Grant date fair value assumptions, dividend yield |  |  |  |  |  | 0.00% |  |
Grant date fair value assumptions, dividend rate, risk-free rate, treasury rate measurement period (in years) |  |  |  |  |  | 3 years |  |
Performance Stock Units | Performance Share Units (PSUs), 2014 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
TSR performance period (in years) |  | 3 years |  |  |  |  |  |
Number of stock awards vested (in shares) |  | 0 |  |  |  |  |  |
Performance Stock Units | Performance Share Units (PSUs), 2013 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
TSR performance period (in years) |  |  | 3 years |  |  |  |  |
Number of stock awards vested (in shares) |  |  | 0 |  |  |  |  |
Performance Stock Units | Performance Share Units (PSUs), 2012 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
TSR performance period (in years) |  |  |  |  | 3 years |  |  |
Number of stock awards vested (in shares) |  |  |  |  | 57,049 |  |  |
Maximum |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Weighted average amortization period remaining for equity awards (in years) |  |  |  |  |  | 2 years |  |
Share-based compensation, vesting period (in years) | 4 years |  |  |  |  |  |  |
Shares of common stock to be purchased in aggregate for all employees (in shares) |  | 450,000 |  |  |  | 450,000 |  |
Maximum | Deferred Stock Units |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Weighted average amortization period remaining for equity awards (in years) |  |  |  |  |  | 2 years |  |
Maximum | Performance Stock Units | Performance Share Units (PSUs), 2015 and 2017 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Equity awards, vesting percentage |  |  |  |  |  | 200.00% |  |
Maximum | Performance Stock Units | Performance Share Units (PSUs), 2016 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Equity awards, vesting percentage |  |  |  |  |  | 200.00% |  |
Award vesting rights, total share return, percentage |  |  |  |  |  | 72.00% |  |
Minimum |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based compensation, vesting period (in years) | 3 years |  |  |  |  |  |  |
Minimum | Performance Stock Units | Performance Share Units (PSUs), 2015 and 2017 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Equity awards, vesting percentage |  |  |  |  |  | 0.00% |  |
Minimum | Performance Stock Units | Performance Share Units (PSUs), 2016 |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Equity awards, vesting percentage |  |  |  |  |  | 0.00% |  |

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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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