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).

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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- 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

The 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

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 (f)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

The estimated measure of the 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

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 (f)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
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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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No definition available.

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Equity Incentive Plan - Valuation Assumptions (Details) - $ / shares					12 Months Ended
	Mar. 01, 2018	Mar. 01, 2017	Jan. 28, 2016	Jun. 01, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Long Term Incentive Plan Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted (in shares)				183,300	244,917	223,922	112,251
Estimated value per unit (in dollars per share)				$ 14.13	$ 16.94	$ 19.20	$ 14.73
Volatility				26.00%
Dividend Yield				4.50%
Risk Free Interest Rate				0.95%
Long Term Incentive Plan Units, Time-Based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted (in shares)	97,968	89,574	72,966
Estimated value per unit (in dollars per share)	$ 16.83	$ 18.53	$ 16.69
Volatility	26.00%	24.00%	28.00%
Dividend Yield	0.00%	0.00%	0.00%
Risk Free Interest Rate	2.07%	0.92%	0.79%
Long Term Incentive Plan Units, Performance-Based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted (in shares)	146,949	134,348	39,285
Estimated value per unit (in dollars per share)	$ 17.02	$ 19.65	$ 11.09
Volatility	26.00%	25.00%	30.00%
Dividend Yield	6.20%	5.80%	5.80%
Risk Free Interest Rate	2.37%	1.47%	1.13%