Consolidated Statements of Equity (Parenthetical)	12 Months Ended
Dec. 31, 2017
Series A Cumulative Redeemable Preferred Stock [Member]
Preferred stock interest rate	7.375%

The percentage rate used to calculate dividend payments on preferred stock.

No definition available.

Name:	us-gaap_PreferredStockDividendRatePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration