Equity - Cash Dividends on Shares of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended	9 Months Ended
Jul. 26, 2018	May 02, 2018	Jan. 30, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Cash dividends declared per common stock (in dollars per share)	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.1	$ 0.10	$ 0.10	$ 0.54	$ 0.3
Cash dividends paid per common stock (in dollars per share)				$ 0.18	$ 0.18	$ 0.18	$ 0.10	$ 0.10	$ 0.10
Common stock, dividends paid										$ 187.0	$ 113.5

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

+ Details

Name:	us-gaap_DividendsCommonStockCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_StockholdersEquityNoteAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration