Represents the aggregate value of common stock which may be sold through sales agents under the stock offering program.

No definition available.

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- Definition

Represents the aggregate value of common stock available to be sold under the stock offering program.

+ References

No definition available.

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- Definition

Payments of Stock Issuance Costs, Agents' Fees

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No definition available.

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Proceeds From Issuance of Common Stock, Net

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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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- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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Aggregate dividends declared during the period for each share of common stock outstanding.

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- Definition

The cash inflow from the additional capital contribution to the entity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
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- Definition

Price of a single share of a number of saleable stocks of a company.

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No definition available.

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- Definition

Number of new stock issued during the period.

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Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands																													1 Months Ended	6 Months Ended		12 Months Ended
	Oct. 16, 2017	Sep. 15, 2017	Aug. 15, 2017	Jul. 31, 2017	Jul. 17, 2017	Jun. 15, 2017	May 15, 2017	May 01, 2017	Apr. 17, 2017	Mar. 15, 2017	Feb. 15, 2017	Jan. 16, 2017	Dec. 15, 2016	Nov. 15, 2016	Nov. 02, 2016	Oct. 15, 2016	Sep. 15, 2016	Aug. 15, 2016	Aug. 01, 2016	Jul. 15, 2016	Jun. 15, 2016	May 16, 2016	May 02, 2016	Apr. 15, 2016	Mar. 15, 2016	Feb. 22, 2016	Feb. 16, 2016	Oct. 22, 2015	Jul. 20, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Apr. 07, 2017	Nov. 08, 2016	May 13, 2016
Class of Stock [Line Items]
Proceeds from sales of common stock																														$ 274,385	$ 0
Common Stock
Class of Stock [Line Items]
Dividend declared (in dollars per share)								$ 0.117500			$ 0.116667				$ 0.116667				$ 0.115833				$ 0.115833			$ 0.115833		$ 0.115833		$ 1.052502		$ 1.389996
Dividends paid (in dollars per share)						$ 0.116667	$ 0.116667		$ 0.116667	$ 0.116667	$ 0.116667	$ 0.115833	$ 0.115833	$ 0.115833		$ 0.115833	$ 0.115833	$ 0.115833		$ 0.115833	$ 0.115833	$ 0.115833		$ 0.115833	$ 0.115833		$ 0.115833			$ 1.052502		$ 1.389996
Common Stock \| Scenario, Forecast
Class of Stock [Line Items]
Dividends paid (in dollars per share)	$ 0.117500	$ 0.117500	$ 0.117500		$ 0.116667
Common Stock \| Non-recognized Subsequent Event
Class of Stock [Line Items]
Dividend declared (in dollars per share)				$ 0.1175
At The Market Program 2017 $300 Million [Domain] \| Non-recognized Subsequent Event
Class of Stock [Line Items]
Number of shares sold																													783,718
Proceeds from sales of common stock																													$ 21,300
At The Market Program 2017 $300 Million [Domain] \| Common Stock
Class of Stock [Line Items]
Common Stock Value Authorized under Stock Offering Program																														$ 300,000			$ 300,000
Aggregate value of common stock available to be sold under the ATM																														$ 142,831
Number of shares sold																														5,956,759
Proceeds from sales of common stock																														$ 157,169
Sales agents' fee																														1,851
Net proceeds																														$ 155,318
At The Market Program 2016 $228 Million [Member] \| Common Stock
Class of Stock [Line Items]
Common Stock Value Authorized under Stock Offering Program																																		$ 228,000
Number of shares sold																														4,799,784		4,763,838
Proceeds from sales of common stock																														$ 117,216		$ 110,887
Sales agents' fee																														1,604		1,550
Net proceeds																														$ 115,612		$ 109,337
At The Market Program 2016 $200 Million [Member] \| Common Stock
Class of Stock [Line Items]
Common Stock Value Authorized under Stock Offering Program																																			$ 200,000
Number of shares sold																																7,326,200
Proceeds from sales of common stock																																$ 171,782
Sales agents' fee																																2,429
Net proceeds																																$ 169,353
At The Market (ATM) Program \| Common Stock
Class of Stock [Line Items]
Number of shares sold																														10,756,543		12,090,038
Proceeds from sales of common stock																														$ 274,385		$ 282,669
Sales agents' fee																														3,455		3,979
Net proceeds																														$ 270,930		$ 278,690
Weighted Average \| At The Market Program 2017 $300 Million [Domain] \| Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)																														$ 26.38
Weighted Average \| At The Market Program 2016 $228 Million [Member] \| Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)																														24.42		$ 23.28
Weighted Average \| At The Market Program 2016 $200 Million [Member] \| Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)																																23.45
Weighted Average \| At The Market (ATM) Program \| Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)																														$ 25.51		$ 23.38