Senior Unsecured Notes and Secured Debt (Details 1) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Debt Instrument [Line Items]
Debt issued, unsecured	$ 2,825,898	$ 7,500
Debt issued, secured	44,606	190,459
Long-term Debt, ending balance	12,233,451
Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term Debt, beginning balance	8,417,447	8,260,038
Debt issued, unsecured	2,850,000	7,500
Debt extinguished	(1,450,000)	(5,000)
Foreign currency	(63,751)	141,855
Long-term Debt, ending balance	$ 9,753,696	$ 8,404,393
Weighted average interest rate
Rate of debt, beginning balance	4.31%	4.25%
Rate on debt issued	0.0457	0.0194
Rate on notes extinguished	0.0346	0.0183
Rate on notes foreign currency	0.0430	0.0424
Rate of debt, ending balance	4.45%	4.29%
Secured Debt
Debt Instrument [Line Items]
Long-term Debt, beginning balance	$ 2,618,408	$ 3,465,066
Debt issued, secured	44,606	190,459
Debt assumed	99,552	23,094
Debt extinguished	(196,573)	(1,003,372)
Principal payments	(42,294)	(47,507)
Foreign currency	(43,944)	92,262
Long-term Debt, ending balance	$ 2,479,755	$ 2,720,002
Weighted average interest rate
Rate of debt, beginning balance	3.76%	4.09%
Rate on debt issued	0.0338	0.0273
Rate on secured debt assumed	0.0430	0.0667
Rate on notes extinguished	0.0566	0.0532
Rate on secured debt principal payment	0.0391	0.0434
Rate on notes foreign currency	0.0329	0.0320
Rate of debt, ending balance	3.79%	3.74%