Debt - Schedule of Credit Facilities (Parenthetical) (Details) (Unsecured Debt, USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Unsecured Debt
Line Of Credit Facility [Line Items]
Unsecured credit facility amount	$ 2,216,127	$ 1,123,354

Amount borrowed under the credit facility as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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