Fair Value of Financial Instruments (Fair Value of Financial Instruments by Balance Sheet Location) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 9,790,744	$ 4,198,209
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	9,971,238	4,203,996
Fair Value, Inputs, Level 3 [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for investment, net	97,587	26,279
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for investment, net	98,902	26,435
Fair Value, Inputs, Level 3 [Member] | Mortgage Notes Payable [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	4,227,494	1,301,114
Fair Value, Inputs, Level 3 [Member] | Mortgage Notes Payable [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	4,328,230	1,305,823
Fair Value, Inputs, Level 3 [Member] | Unsecured Debt [Member] | Senior Unsecured Note [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	2,546,089	0
Fair Value, Inputs, Level 3 [Member] | Unsecured Debt [Member] | Senior Unsecured Note [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	2,568,117	0
Fair Value, Inputs, Level 3 [Member] | Unsecured Debt [Member] | Trust Preferred Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	26,579	26,548
Fair Value, Inputs, Level 3 [Member] | Unsecured Debt [Member] | Trust Preferred Notes [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	23,485	23,345
Fair Value, Inputs, Level 3 [Member] | Convertible Debt [Member] | Convertible Senior Notes [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	975,003	972,490
Fair Value, Inputs, Level 3 [Member] | Convertible Debt [Member] | Convertible Senior Notes [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	1,035,581	976,629
Fair Value, Inputs, Level 3 [Member] | Line of Credit [Member] | Credit Facilities [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	1,896,000	1,819,800
Fair Value, Inputs, Level 3 [Member] | Line of Credit [Member] | Credit Facilities [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	1,896,000	1,819,800
Fair Value, Inputs, Level 3 [Member] | Term Loan [Member] | Secured Term Loan [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	51,296	58,979
Fair Value, Inputs, Level 3 [Member] | Term Loan [Member] | Secured Term Loan [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	51,411	59,049
Fair Value, Inputs, Level 3 [Member] | Other Debt Obligations [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	68,283	19,278
Fair Value, Inputs, Level 3 [Member] | Other Debt Obligations [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 68,414	$ 19,350