v3.10.0.1

Long-Term Incentive Plan (Weighted-Average Grant Date Fair Values) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Long Term Incentive Plan [Line Items]
Units granted (in shares)	302,487
Weighted-Average Grant Date Fair Value (in dollars per share)	$ 73.03
Performance Shares [Member]
Long Term Incentive Plan [Line Items]
Units granted (in shares)	218,923	189,544	193,344
Weighted-Average Grant Date Fair Value (in dollars per share)	$ 73.80	$ 82.34	$ 70.29
Time-Based Awards [Member]
Long Term Incentive Plan [Line Items]
Units granted (in shares)	83,564	30,604	39,301
Weighted-Average Grant Date Fair Value (in dollars per share)	$ 71.03	$ 79.10	$ 64.76

X

- Definition

Long Term Incentive Plan [Line Items]

+ References

No definition available.

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X

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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X

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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