Describes the maximum potential amount of consideration, undiscounted, that could be transferred under the registration payment arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

Name:	us-gaap_RegistrationPaymentArrangementMaximumPotentialConsideration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Common Stock (Details Textual) - USD ($) $ in Millions		3 Months Ended
Common Stock (Details Textual) - USD ($) $ in Millions	May 06, 2015	Mar. 31, 2017	Mar. 31, 2015
ATM Program [Member]
Class of Stock [Line Items]
Gross Amount Remaining To Be Issued		$ 36.2
Common Stock [Member]
Class of Stock [Line Items]
Registration Payment Arrangement, Maximum Potential Consideration			$ 500.0
Common Stock [Member] \| ATM Program [Member]
Class of Stock [Line Items]
Value Of Equity Instruments To Be Issued	$ 100.0