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Stock Option and Incentive Plan Schedule of Stock Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	540,441	540,441	547,129	547,129
Outstanding, Weighted Average Exercise Price	$ 96.35	$ 96.35	$ 96.38	$ 96.38
Number Exercisable		540,441	514,360
Exercisable, Weighted Average Exercise Price		$ 96.35	$ 96.32
Exercise Price of $86.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	2 years 1 month 6 days
Number Outstanding at period end	118,502
Outstanding, Weighted Average Exercise Price	$ 86.86
Number Exercisable	118,502
Exercisable, Weighted Average Exercise Price	$ 86.86
Exercise Price of $95.69 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	4 years 3 months 18 days
Number Outstanding at period end	54,282
Outstanding, Weighted Average Exercise Price	$ 95.69
Number Exercisable	54,282
Exercisable, Weighted Average Exercise Price	$ 95.69
Exercise Price of $98.46 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	4 years 1 month 6 days
Number Outstanding at period end	202,030
Outstanding, Weighted Average Exercise Price	$ 98.46
Number Exercisable	202,030
Exercisable, Weighted Average Exercise Price	$ 98.46
Exercise Price of $100.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	3 years 1 month 6 days
Number Outstanding at period end	165,627
Outstanding, Weighted Average Exercise Price	$ 100.77
Number Exercisable	165,627
Exercisable, Weighted Average Exercise Price	$ 100.77
Unvested 2016 - 2018 MYLTIP Units [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted-average period (years)	2 years 3 months 18 days

X

- 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.

+ 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 (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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=96867065&loc=d3e5070-113901

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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

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=96867065&loc=d3e5070-113901

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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=96867065&loc=d3e5070-113901

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock 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)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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