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- Definition

Percentage of Stock Award Subject to Vesting

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Award Vesting Date

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award Percentage of Annual Bonus Settled With Share Awards

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- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 740
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65880886&loc=d3e23524-113945

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-Name Accounting Standards Codification
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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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- Definition

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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).

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

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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.

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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- Definition

Net number of share options (or share units) granted during the period.

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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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- Definition

Price of a single share of a number of saleable stocks of a company.

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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Share-Based Compensation Plans - Additional Information (Detail) - USD ($)		12 Months Ended			124 Months Ended	160 Months Ended
	Jun. 12, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2016	Jun. 11, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax expense resulting from stock-based compensation deductions in excess of amounts reported for financial reporting purposes		$ 100,000	$ 50,000	$ 40,000
Number of options exercisable		450,000				450,000
Stock options awarded		0	200,000	325,000
Strike price per share			$ 28.37	$ 31.74
Stock options forfeited		200,000		125,000
Stock options forfeited, strike price per share		$ 28.37		$ 19.60
Compensation expense, options		$ 300,000	$ 400,000	$ 300,000
Fair value of company's shares		$ 38.21				$ 38.21
Weighted average fair value of options granted			$ 8.69	$ 7.92
Compensation expense, restricted stock		$ 3,200,000	$ 3,500,000	$ 2,600,000
Exercise price applicable		$ 25.13	$ 25.94	$ 25.38	$ 18.62	$ 25.13
Subject to a clawback which is based on the remeasurement of accident year results on the third anniversary after the options provisionally vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options exercisable		250,000				250,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense for non-vested restricted stock		$ 2,900,000				$ 2,900,000
Weighted average life of non-vested restricted stock		1 year 4 months 24 days
Number of shares issued		156,531	174,828	132,302	1,116,348	1,580,009
Weighted average fair value per share		$ 29.44	$ 28.24	$ 25.67
Restricted Stock \| Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		121,346	138,507	95,694	711,068	1,066,615
Weighted average fair value per share		$ 28.97	$ 28.37	$ 25.37
Restricted Stock \| Key Employees \| Time Based Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		96,585	83,875	78,166
Restricted Stock \| Key Employees \| Stock vest first anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		16.50%	16.50%	16.50%
Vesting period		1 year	1 year	1 year
Restricted Stock \| Key Employees \| Stock vest second anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		16.50%	16.50%	16.50%
Vesting period		2 years	2 years	2 years
Restricted Stock \| Key Employees \| Stock vest third anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		17.00%	17.00%	17.00%
Vesting period		3 years	3 years	3 years
Restricted Stock \| Key Employees \| Vesting Schedule Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		100.00%	100.00%	100.00%
Vesting period		3 years	3 years	3 years
Percentage of stock award subject to vesting		50.00%	50.00%	50.00%
Restricted Stock \| Key Employees \| First Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued				5,671
Percentage of shares vested on each anniversary of the grant date				33.33%
Vesting period				3 years
Restricted Stock \| Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		11,199	10,574	11,857
Percentage of shares vested on each anniversary of the grant date		33.33%	33.33%	33.33%
Vesting period		3 years	3 years	3 years
Percentage of annual bonus eligible to be paid in shares		50.00%
Restricted Stock \| Non Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		35,185	36,321	36,608
Weighted average fair value per share		$ 31.05	$ 27.73	$ 26.46
Restricted Stock \| Non Employee Director \| Revised Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued	18,838
Restricted Stock \| Chief Executive Officer And Other Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued			44,058
Percentage of shares vested on each anniversary of the grant date			100.00%
Vesting date			Jan. 01, 2018
Restricted Stock \| Another Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		5,309
Percentage of shares vested on each anniversary of the grant date		100.00%
Vesting date		Feb. 07, 2019
Restricted Stock \| Other Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		8,253
Restricted Stock \| Other Key Employees \| Stock vest first anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		33.00%
Restricted Stock \| Other Key Employees \| Stock vest second anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		33.00%
Restricted Stock \| Other Key Employees \| Stock vest third anniversary of the grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date		34.00%
Time Based Option Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options exercisable		450,000				450,000
Stock options awarded				325,000
Stock options forfeited				125,000
Time Based Option Award \| Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options awarded		300,000
Strike price per share		$ 17.87
Stock options forfeited				25,000
Stock options granted (net)				300,000
Percentage of shares vested on each anniversary of the grant date		33.33%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization expense related to options in 2017		$ 300,000
Stock Options \| Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options awarded				300,000
Exercise price applicable				$ 25.00
Stock Options \| Chief Executive Officer \| December 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date				20.00%
Stock Options \| Chief Executive Officer \| December 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date				30.00%
Stock Options \| Chief Executive Officer \| December 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested on each anniversary of the grant date				50.00%
Performance Based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options awarded			200,000
Strike price per share			$ 28.37
Stock options forfeited		200,000
Stock options forfeited, strike price per share		$ 28.37
Ordinary Shares A \| Share Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant							2,000,000
Ordinary Shares A \| A Former Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceed from exercise of options		$ 0	$ 0	$ 0