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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
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-Name Staff Accounting Bulletin (SAB)
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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.

+ References

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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
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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.

+ References

No definition available.

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

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-Topic 718
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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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

Percentage of vesting of share-based compensation awards.

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- Definition

Number of share options (or share units) exercised during the current period.

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-Publisher FASB
-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

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Share-Based Compensation , Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended				2 Months Ended	3 Months Ended	12 Months Ended
	Jul. 24, 2014	Jun. 20, 2013	Jul. 31, 2015	May. 31, 2015	Apr. 30, 2015	Feb. 28, 2015	Feb. 18, 2014	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 20, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from Stock Options Exercised									$ 95	$ 127	$ 201
Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Available for Grant												1,744,000
Number of Shares Authorized												1,750,000
Director Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Available for Grant										75,674
Number of Shares Authorized										175,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares									216,800	117,250	371,300
Weighted Average Grant Date Fair Value			$ 67.57	$ 62.94	$ 63.81				$ 64.32	$ 49.97	$ 47.19
Share-based Compensation Expense									$ 7,100	$ 4,900	$ 3,200
Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares									6,000
Weighted Average Grant Date Fair Value									$ 66.10
Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares			20,000	25,000	145,000				45,250
Weighted Average Grant Date Fair Value									$ 52.54
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercises in Period									(8,000)	(12,250)	(9,700)
2004 non-employee plan [Member] \| Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from Stock Options Exercised									$ 100
Exercises in Period									(5,584)
Director [Member] \| Restricted Stock [Member] \| Director Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares						19,800	14,000
Weighted Average Grant Date Fair Value						$ 65.87	$ 48.01
Chief Executive Officer [Member] \| Performance Shares [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares		175,000
Chief Executive Officer [Member] \| Market Condition Shares [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares									50,000	50,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number										37,500
Chief Executive Officer [Member] \| Service-based Shares [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares		75,000
Chief Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares		250,000
Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares									58,000
Weighted Average Grant Date Fair Value									$ 48.93
Share-based Compensation Award, Tranche Six [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares					72,500
Share-based Compensation Award, Tranche Two [Member] \| Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage								35.00%
Share-based Compensation Award, Tranche Two [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage			35.00%	35.00%	30.00%
Share-based Compensation Award, Tranche Three [Member] \| Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage								20.00%
Share-based Compensation Award, Tranche Three [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage			20.00%	20.00%	35.00%
Share-based Compensation Award, Tranche Four [Member] \| Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage								5.00%
Share-based Compensation Award, Tranche Four [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage			5.00%	5.00%	10.00%
2019 [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									20.00%
2019 [Member] \| Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									30.00%
June 20, 2020 [Member] \| Chief Executive Officer [Member] \| Service-based Shares [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares	150,000
June 20, 2020 [Member] \| Chief Executive Officer [Member] \| Market and Performance Shares [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares	100,000
2020 [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									5.00%
2020 [Member] \| Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									35.00%
2021 [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									5.00%
2021 [Member] \| Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									10.00%
2018 [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									35.00%
2018 [Member] \| Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									20.00%
2022 [Member] \| Executive Officer [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									5.00%
2017 [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage									35.00%
Share-based Compensation Award, Tranche Five [Member] \| Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage								5.00%
Share-based Compensation Award, Tranche Five [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage			5.00%	5.00%	5.00%
Share-based Compensation Award, Tranche One [Member] \| Restricted Stock [Member] \| Two Thousand Fifteen Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage								35.00%
Share-based Compensation Award, Tranche One [Member] \| Restricted Stock [Member] \| 2009 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Rights, Percentage			35.00%	35.00%	20.00%