v3.8.0.1

Stockholders' Equity - Additional Information (Detail) - USD ($) |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Jul. 08, 2015 | Nov. 11, 2014 | Sep. 30, 2017 | Sep. 30, 2015 | Nov. 06, 2015 | Nov. 05, 2014
Stockholders Equity [Line Items] |  |  |  |  |  |
Common stock repurchased, Shares |  |  | 196,190 |  |  |
Payments for repurchase of common stock |  |  | $ 4,702,000 | $ 20,000,000 |  |
Stock repurchased average price per share |  |  | $ 23.97 |  |  |
Remaining amount available for repurchases of shares |  |  | $ 25,300,000 |  |  |
Accelerated Share Repurchase Program [Member] |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Maximum payments for repurchase of common stock |  |  |  |  | $ 20,000,000 | $ 30,000,000
Common stock repurchased, Shares |  | 847,864 |  |  |  |
Fair value of common stock |  | $ 16,000,000 |  |  |  |
Reduction in common stock |  | 100,000 |  |  |  |
Reduction in additional paid-in capital |  | 2,500,000 |  |  |  |
Reduction in retained earnings |  | 13,500,000 |  |  |  |
Initial payment to bank reported as reduction in retained earnings |  | $ 4,000,000 |  |  |  |
Accelerate share repurchase program, price per share |  | $ 23.59 |  |  |  |
Accelerated Share Repurchase Program [Member] | Investment Bank [Member] |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Common stock repurchased, Shares |  | 758,143 |  |  |  |
Fair value of common stock |  | $ 20,000,000 |  |  |  |
Transaction One [Member] | Accelerated Share Repurchase Program [Member] |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Common stock repurchased, Shares |  | 758,143 |  |  |  |
Transaction Two [Member] | Accelerated Share Repurchase Program [Member] |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Common stock repurchased, Shares | 89,721 |  |  |  |  |

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- Definition Final price paid per share for the purchase of the targeted number of shares, determined by an average market price over a fixed period of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653 + Details
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- Definition Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 Reference 2: 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 Reference 3: 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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- Definition Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. + 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
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