Disclosure about Fair Value of Financial Instruments - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Financial assets:
Equity securities		$ 6,600
Restricted cash	[1]		$ 100,849
Carrying Amount
Financial assets:
Equity securities		6,600	15,685
Cash and cash equivalents		1,678,770	284,917
Restricted cash		147,473	100,849
Foreign currency forward contracts, interest rate swaps and cross currency swaps		165,968	18,554
Financial liabilities:
Borrowings under unsecured credit facility and commercial paper program		0	1,587,597
Senior unsecured notes		11,815,972	10,336,513
Secured debt		2,619,678	2,990,962
Foreign currency forward contracts, interest rate swaps and cross currency swaps		64,077	53,601
Redeemable OP unitholder interests		97,179	121,440
Carrying Amount | Mortgage loans receivable
Financial assets:
Loans receivable		100,782	145,686
Carrying Amount | Other real estate loans receivable
Financial assets:
Loans receivable		124,089	124,696
Carrying Amount | Non-real estate loans receivable
Financial assets:
Loans receivable		373,835	336,854
Fair Value
Financial assets:
Equity securities		6,600	15,685
Cash and cash equivalents		1,678,770	284,917
Restricted cash		147,473	100,849
Foreign currency forward contracts, interest rate swaps and cross currency swaps		165,968	18,554
Financial liabilities:
Borrowings under unsecured credit facility and commercial paper program		0	1,587,597
Senior unsecured notes		12,890,274	11,400,571
Secured debt		2,668,133	3,041,893
Foreign currency forward contracts, interest rate swaps and cross currency swaps		64,077	53,601
Redeemable OP unitholder interests		92,373	121,440
Fair Value | Mortgage loans receivable
Financial assets:
Loans receivable		107,407	150,217
Fair Value | Other real estate loans receivable
Financial assets:
Loans receivable		124,291	128,512
Fair Value | Non-real estate loans receivable
Financial assets:
Loans receivable		$ 419,325	$ 379,239

[1] The consolidated balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements.