Indebtedness - Debt Issuance Costs and Discounts (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Indebtedness
Cash paid for interest	$ 803,728	$ 811,971	$ 814,729
Debt issuance cost
Debt issuance costs	187,514	204,189
Accumulated amortization	(86,234)	(108,014)
Debt issuance costs	101,280	96,175
Amortization of Debt Issuance Costs and Discounts
Amortization of debt issuance costs	21,499	21,445	21,707
Amortization of debt discounts/(premiums)	$ 1,571	$ 1,618	$ 1,357

Amount of accumulated amortization of debt issuance costs.

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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