Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		21 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Dec. 20, 2018	Apr. 05, 2017
Derivative [Line Items]
Interest expense related to payments on interest rate swaps	$ 6,724			$ 6,386			$ 20,329	$ 22,699
Increase (decrease) in fair value of derivative contracts	(5,733)	$ (18,606)	$ (9,853)	$ 1,429	$ 2,563	$ 5,982	(34,192)	$ 9,974
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
Outstanding debt											400,000
Interest Rate Swap | Term Loan Maturing April 27, 2022
Derivative [Line Items]
Derivative instruments, notional amount											200,000	200,000
Interest Rate Swap | Term Loan Maturing December 17,2021
Derivative [Line Items]
Derivative instruments, notional amount											200,000	$ 200,000
Interest Rate Swap | Term Loan Maturing December 17 2023
Derivative [Line Items]
Derivative instruments, notional amount											200,000
Interest Rate Swap | Term Loan Maturing April 27 2024
Derivative [Line Items]
Derivative instruments, notional amount	100,000						100,000		100,000		$ 200,000
Cash flow hedging | Interest Rate Swap
Derivative [Line Items]
Derivative Asset, fair Value										$ 5,300
Derivative Liability, fair Value	25,100						25,100		25,100	3,000
Derivative, Fair Value, Net	$ (25,141)						$ (25,141)		$ (25,141)	$ 2,343