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Stock-Based Compensation - Schedule of Information Related to Outstanding SOSARS (Detail) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Exercised | (26,000) | (110,000) | (137,000)
Stock Only Stock Appreciation Rights (SOSARs) [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Outstanding | 1,864,707 | 1,977,133 | 2,121,454
Granted | 423,590 | 281,881 | 368,687
Exercised | (70,347) | (364,465) | (435,562)
Canceled / forfeited | (18,208) | (29,842) | (77,446)
Ending Balance, Outstanding | 2,199,742 | 1,864,707 | 1,977,133
Exercisable at December 31 | 1,504,599 | 1,285,998 | 1,330,816
Vested and expected to vest | 2,178,708 | 1,754,295 | 1,863,244
Beginning Balance, Weighted Average Exercise Price, Outstanding | $ 16.20 | $ 13.91 | $ 12.93
Weighted Average Exercise Price, Granted | 24.62 | 29.78 | 18.51
Weighted Average Exercise Price, Exercised | 14.12 | 13.99 | 12.63
Weighted Average Exercise Price, Canceled / forfeited | 25.41 | 19.36 | 16.28
Ending Balance, Weighted Average Exercise Price, Outstanding | 17.82 | 16.20 | 13.91
Weighted Average Exercise Price, Exercisable at December 31, | 14.48 | 12.94 | 12.58
Weighted average grant date fair value per share | $ 7.46 | $ 9.81 | $ 5.74
Aggregate grant date fair value | $ 3,134 | $ 2,764 | $ 2,103
Black-Scholes assumptions |  |  |
Dividend yield | 1.94% | 1.48% | 2.16%
Risk free rate of return | 1.64% | 1.74% | 1.01%
Volatility | 36.38% | 37.59% | 39.58%
Expected life | 6 years | 6 years | 6 years
Compensation expense | $ 2,645 | $ 2,086 | $ 1,591

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- Definition Share based compensation arrangement by share based payment award options grant date fair value. + References No definition available. + Details
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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + 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 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 Weighted average expected volatility rate of share-based compensation awards. + 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 number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option 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)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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