Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		18 Months Ended
Derivative Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Dec. 20, 2018	Apr. 05, 2017
Derivative [Line Items]
Interest expense related to payments on interest rate swaps	$ 6,459		$ 8,203		$ 13,605	$ 16,313
Increase (decrease) in fair value of derivative contracts	(18,606)	$ (9,853)	$ 2,563	$ 5,982	(28,459)	$ 8,545
Term Loan
Derivative [Line Items]
Outstanding debt	700,000				700,000		$ 700,000
Interest Rate Swap
Derivative [Line Items]
Derivative instruments, notional amount									$ 400,000	$ 400,000
Ineffectiveness recognized							0
Interest Rate Swap \| Term Loan
Derivative [Line Items]
Aggregate principal amount	$ 400,000				$ 400,000		$ 400,000			400,000
Outstanding debt									400,000
Interest Rate Swap \| Term Loan Maturing April 27, 2022
Derivative [Line Items]
Derivative instruments, notional amount									200,000	200,000
Weighted average effective fixed interest rate	3.90%				3.90%		3.90%
Interest Rate Swap \| Term Loan Maturing December 17,2021
Derivative [Line Items]
Derivative instruments, notional amount									$ 200,000	$ 200,000
Weighted average effective fixed interest rate										3.30%
Average variable interest rate	1.30%				1.30%		1.30%
Interest Rate Swap \| Term Loan Maturing December 17 2023
Derivative [Line Items]
Derivative instruments, notional amount	$ 100,000				$ 100,000		$ 100,000
Interest Rate Swap \| Term Loan Maturing April 27 2024
Derivative [Line Items]
Derivative instruments, notional amount	100,000				100,000		100,000
Interest Rate Swap \| Term Loan Maturing January 2, 2020
Derivative [Line Items]
Derivative instruments, notional amount	$ 200,000				$ 200,000		$ 200,000
Weighted average effective fixed interest rate	3.90%				3.90%		3.90%
Average variable interest rate	1.30%				1.30%		1.30%
Cash flow hedging \| Interest Rate Swap
Derivative [Line Items]
Derivative instruments, notional amount	$ 1,000,000				$ 1,000,000		$ 1,000,000	$ 1,000,000
Derivative Asset, fair Value								5,300
Derivative Liability, fair Value	19,200				19,200		19,200	3,000
Derivative, Fair Value, Net	$ (19,176)				$ (19,176)		$ (19,176)	$ 2,343