Number of warrants or rights granted.

No definition available.

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- Definition

The maximum 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

No definition available.

+ Details

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The minimum 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

No definition available.

+ Details

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- Definition

The weighted-average expected dividend yield.

+ References

No definition available.

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- Definition

The number of incentive plans.

+ References

No definition available.

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- Definition

Represents the maximum increase (expressed as a percentage of target level) in the number of shares a participant receives based on the level of achievement of performance goals.

+ References

No definition available.

+ Details

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- Definition

The proportion of new awards that will vest each year.

+ References

No definition available.

+ Details

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- Definition

Represents the potential lowest number of shares of common stock that a participant could receive based on the level of achievement of performance goals.

+ References

No definition available.

+ Details

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- Definition

Share-Based Compensation Information [Abstract]

+ References

No definition available.

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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
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-Topic 718
-SubTopic 10
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- Definition

Number of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 1
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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

+ Details

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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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

Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 55
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=65896087&loc=d3e11374-113907

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Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

+ References

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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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- References

No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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).

+ References

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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- Definition

Amount of cash paid related to share-based compensation liabilities.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- References

No definition available.

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- Definition

The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- Definition

Weighted average expected volatility rate of share-based compensation awards.

+ References

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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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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).

+ References

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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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- References

No definition available.

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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

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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

+ References

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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.

+ References

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- Definition

Net 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.

+ References

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ References

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

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

+ References

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

+ References

No definition available.

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- References

No definition available.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

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

+ 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(29))
-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 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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(28))
-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

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Share-Based Compensation (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award
Number of stock appreciation rights outstanding						0
Number of stock appreciation rights granted					0	0	0
Share-Based Compensation Information
Share-based Compensation Arrangement by Share-based Payment Award, Number of plans					4
Share-based compensation expense \| $	$ 1,293	$ 1,321	$ 4,915	$ 5,747	$ 3,875	$ 8,222	$ 7,314
Excess Tax Benefit on Stock Plans \| $			0	$ 447	$ 686	$ 859	$ 1,793
Valuation assumptions used for the 2016, 2015 and 2014 grants
Expected volatility, minimum					29.00%	32.00%	47.00%
Expected volatiity, maximum					32.00%	36.00%	50.00%
Weighted-average expected volatility					32.00%	36.00%	50.00%
Expected dividend yield, minimum					1.30%	1.10%	1.10%
Expected dividend yield, maximum					1.50%	1.20%	1.30%
Weighted-average expected dividend yield					1.30%	1.20%	1.30%
Expected term, in years					5 years	5 years	6 years
Risk-free interest rate, minimum					1.10%	1.40%	1.80%
Risk-free interest rate, maximum					1.40%	1.60%	2.00%
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Excess Tax Benefit from Share-based Compensation, Operating Activities \| $			$ 1,149
2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares authorized for future awards (in shares)					1,500,000
Amended 2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares authorized for future awards (in shares)					2,600,000
Shares reserved for issuance (in shares)					656,339
All Plans Excluding 2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares reserved for issuance (in shares)					252,598
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Ratio of new awards that vest each year					one-third
Vesting period of new awards granted (in years)					3 years
Contractual term of new awards (in years)					10 years
Shares activity
Outstanding at beginning of year (in shares)			1,113,382	1,018,958	1,018,958
Granted (in shares)					258,895
Exercised (in shares)					(135,744)
Forfeited (in shares)					(23,028)
Expired (in shares)					(5,699)
Outstanding at end of year (in shares)					1,113,382	1,018,958
Exercisable at end of year (in shares)					736,650
Weighted-Average Exercise Price
Outstanding at beginning of year (in dollars per share) \| $ / shares			$ 42.34	$ 39.69	$ 39.69
Granted (in dollars per share) \| $ / shares					52.80
Exercised (in dollars per share) \| $ / shares					38.82
Forfeited (in dollars per share) \| $ / shares					59.46
Expired (in dollars per share) \| $ / shares					60.26
Outstanding at end of year (in dollars per share) \| $ / shares					42.34	$ 39.69
Exercisable at end of year \| $ / shares					34.75
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Weighted-average grant date fair value (in dollars per share) \| $ / shares					$ 13.61	$ 20.08	$ 26.93
Total intrinsic value of stock options exercised \| $					$ 3,408	$ 1,702	$ 2,972
Aggregate intrinsic value of options outstanding \| $					32,152
Aggregate intrinsic value of options exercisable \| $					$ 26,868
Weighted-average remaining contractual life for options outstanding (in years)					5 years 10 months 24 days
Weighted-average remaining contractual life for options exercisable (in years)					4 years 4 months 24 days
Unrecognized compensation cost for nonvested options \| $					$ 2,103
Compensation cost not yet recognized, weighted-average period for recognition (in years)					1 year 3 months 18 days
Restricted Share Awards
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period of new awards granted (in years)			3 years		3 years
Shares activity
Nonvested at beginning of year (in shares)			117,234	138,819	138,819
Granted (in shares)			19,971		27,921
Vested (in shares)					(49,306)
Forfeited (in shares)					(200)
Nonvested at end of year (in shares)					117,234	138,819
Weighted-Average Exercise Price
Nonvested at beginning of year (in dollars per share) \| $ / shares			$ 47.62	$ 43.83	$ 43.83
Granted (in dollars per share) \| $ / shares					53.02
Vested (in dollars per share) \| $ / shares					39.96
Forfeited (in dollars per share) \| $ / shares					61.26
Nonvested at end of year (in dollars per share) \| $ / shares					$ 47.62	$ 43.83
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Weighted-average grant date fair value (in dollars per share) \| $ / shares			$ 73.16
Fair value of shares vested \| $			$ 1,295	$ 1,835	$ 1,970	$ 1,054	827
Unrecognized compensation cost for nonvested options \| $					$ 1,679
Compensation cost not yet recognized, weighted-average period for recognition (in years)					1 year 10 months
Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award
Maximum increase in the number of shares of common stock a participant receives based on the achievement of performance goals (as a percent)					200.00%
Lowest potential number of shares of common stock that could be received based on the achievement level of performance goals					0
Vesting period of new awards granted (in years)					3 years
Shares activity
Nonvested at beginning of year (in shares)			129,096	141,374	141,374
Granted (in shares)					58,454
Vested (in shares)					(36,054)
Forfeited (in shares)					(34,678)
Nonvested at end of year (in shares)					129,096	141,374
Weighted-Average Exercise Price
Nonvested at beginning of year (in dollars per share) \| $ / shares			$ 59.30	$ 56.07	$ 56.07
Granted (in dollars per share) \| $ / shares					52.56
Vested (in dollars per share) \| $ / shares					47.25
Forfeited (in dollars per share) \| $ / shares					47.30
Nonvested at end of year (in dollars per share) \| $ / shares					$ 59.30	$ 56.07
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Fair value of shares vested \| $					$ 1,703	$ 1,713	4,346
Unrecognized compensation cost for nonvested options \| $					$ 5,642
Compensation cost not yet recognized, weighted-average period for recognition (in years)					1 year 8 months 12 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period of new awards granted (in years)					3 years
Shares activity
Nonvested at beginning of year (in shares)			31,038	32,646	32,646
Granted (in shares)					15,450
Vested (in shares)					(13,190)
Forfeited (in shares)					(3,868)
Nonvested at end of year (in shares)					31,038	32,646
Weighted-Average Exercise Price
Nonvested at beginning of year (in dollars per share) \| $ / shares			$ 60.47	$ 66.89	$ 66.89
Granted (in dollars per share) \| $ / shares					54.35
Vested (in dollars per share) \| $ / shares					68.80
Forfeited (in dollars per share) \| $ / shares					61.83
Nonvested at end of year (in dollars per share) \| $ / shares					$ 60.47	$ 66.89
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Fair value of shares vested \| $					$ 907	$ 10	0
Unrecognized compensation cost for nonvested options \| $					$ 723
Compensation cost not yet recognized, weighted-average period for recognition (in years)					1 year 2 months 12 days
Share-Based Liabilities
Share-based Compensation Arrangement by Share-based Payment Award Additional Disclosures
Total share-based liabilities \| $					$ 155	149
Amounts paid out related to share-based liability awards \| $					$ 62	$ 53	$ 275