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Mandatorily Redeemable Term Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Feb. 29, 2012 | Dec. 31, 2017
Class of Stock [Line Items] |  |
Preferred stock mandatory redemption date | Jan. 31, 2017 |
Write -off of unamortized offering costs |  | $ 0.2
Series C Preferred Stock |  |
Class of Stock [Line Items] |  |
Redeemable preferred stock, dividend rate percentage (as percent) | 7.125% |
Mandatorily Redeemable Preferred Stock |  |
Class of Stock [Line Items] |  |
Redeemable preferred stock, shares issued (in shares) | 1,540,000 |
Redeemable preferred stock, par value (in dollars per share) | $ 0.001 |
Public offering price (in dollars per share) | $ 25.00 |
Gross proceeds of the offering | $ 38.5 |
Net proceeds, after deducting offering expenses | $ 36.7 |

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- Definition Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Date the preferred stock has been redeemed, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21564-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 + Details
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- Definition Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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