Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Financial Liabilities:
Contingent consideration				$ 6,200
Derivatives:
Increase in contingent consideration value	$ 100	$ 1,900	$ (1,000)
Interest Rate Swap
Derivatives:
Asset for Swaps				12,000
Recurring
Financial Assets:
Cash and cash equivalents	97,884		97,884	118,804
Restricted cash	11,425		11,425	11,065
Total	109,309		109,309	129,869
Financial Liabilities:
Contingent consideration	5,520		5,520	6,500
Total debt	1,786,397		1,786,397	1,780,547
Total	1,791,917		1,791,917	1,787,047
Recurring | Interest Rate Swap
Derivatives:
Asset for Swaps	26,856		26,856	11,985
Derivative Liability	522		522
Recurring | Level 1
Financial Assets:
Cash and cash equivalents	97,884		97,884	118,804
Restricted cash	2,271		2,271	0
Total	100,155		100,155	118,804
Financial Liabilities:
Contingent consideration	0		0	0
Total debt	0		0	0
Total	0		0	0
Recurring | Level 1 | Interest Rate Swap
Derivatives:
Asset for Swaps	0		0	0
Derivative Liability	0		0
Recurring | Level 2
Financial Assets:
Cash and cash equivalents	0		0	0
Restricted cash	9,154		9,154	11,065
Total	9,154		9,154	11,065
Financial Liabilities:
Contingent consideration	0		0	0
Total debt	1,786,397		1,786,397	1,780,547
Total	1,786,397		1,786,397	1,780,547
Recurring | Level 2 | Interest Rate Swap
Derivatives:
Asset for Swaps	26,856		26,856	11,985
Derivative Liability	522		522
Recurring | Level 3
Financial Assets:
Cash and cash equivalents	0		0	0
Restricted cash	0		0	0
Total	0		0	0
Financial Liabilities:
Contingent consideration	5,520		5,520	6,500
Total debt	0		0	0
Total	5,520		5,520	6,500
Recurring | Level 3 | Interest Rate Swap
Derivatives:
Asset for Swaps	0		0	$ 0
Derivative Liability	$ 0		$ 0