Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Financial Liabilities:
Contingent consideration		$ 6,200
Derivatives:
Increase in contingent consideration value	$ 400
Interest Rate Swap
Derivatives:
Asset for Swaps		12,000
Recurring
Financial Assets:
Cash and cash equivalents	123,698	118,804
Restricted cash	8,609	11,065
Total Financial Assets	132,307	129,869
Financial Liabilities:
Contingent consideration	6,900	6,500
Total debt	1,734,043	1,780,547
Total Financial Liabilities	1,740,943
Recurring | Interest Rate Swap
Derivatives:
Asset for Swaps	18,542	11,985
Liability for Swaps	1,046
Recurring | Level 1
Financial Assets:
Cash and cash equivalents	123,698	118,804
Restricted cash	0	0
Total Financial Assets	123,698	118,804
Financial Liabilities:
Contingent consideration	0	0
Total debt	0	0
Total Financial Liabilities	0
Recurring | Level 1 | Interest Rate Swap
Derivatives:
Asset for Swaps	0	0
Liability for Swaps	0
Recurring | Level 2
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	8,609	11,065
Total Financial Assets	8,609	11,065
Financial Liabilities:
Contingent consideration	0	0
Total debt	1,734,043	1,780,547
Total Financial Liabilities	1,734,043
Recurring | Level 2 | Interest Rate Swap
Derivatives:
Asset for Swaps	18,542	11,985
Liability for Swaps	1,046
Recurring | Level 3
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Total Financial Assets	0	0
Financial Liabilities:
Contingent consideration	6,900	6,500
Total debt	0	0
Total Financial Liabilities	6,900
Recurring | Level 3 | Interest Rate Swap
Derivatives:
Asset for Swaps	0	$ 0
Liability for Swaps	$ 0