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Stockholders' Equity - Summary of Shares Repurchased Under Stock Purchase Program (Detail) - $ / shares | 12 Months Ended |
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2017
Summary Of Shares Repurchased Under Stock Purchase Program [Abstract] |  |  |
Number of shares repurchased | 200,000 | 56,894 |
Average price of shares repurchased | $ 27.62 | $ 29.10 |
Shares remaining to be repurchased | 300,000 | 332,552 | 300,000

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- Definition Summary of shares repurchased under stock purchase program. + References No definition available. + Details
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- Definition Number of stock bought back by the entity at the exercise price or redemption price. + 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 + Details
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- Definition The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. + References No definition available. + Details
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- Definition Total cost of shares repurchased divided by the total number of shares repurchased. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details
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