Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized losses in connection with contingent consideration	$ 900	$ 900
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	72,367	72,367	$ 99,090
Restricted cash	11,009	11,009	10,926
Marketable securities	22,570	22,570	22,709
Total Financial Assets	105,946	105,946	132,725
Contingent consideration	8,900	8,900
Total debt	1,677,100	1,677,100	1,315,473
Total Financial Liabilities	1,686,000	1,686,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	72,367	72,367	99,090
Restricted cash	0	0	0
Marketable securities	22,570	22,570	22,709
Total Financial Assets	94,937	94,937	121,799
Contingent consideration	0	0
Total debt	0	0	0
Total Financial Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0	0
Restricted cash	11,009	11,009	10,926
Marketable securities	0	0	0
Total Financial Assets	11,009	11,009	10,926
Contingent consideration	0	0
Total debt	1,677,100	1,677,100	1,315,473
Total Financial Liabilities	1,677,100	1,677,100
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Marketable securities	0	0
Total Financial Assets	0	0
Contingent consideration	8,900	8,900
Total debt	0	0
Total Financial Liabilities	8,900	8,900
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability for interest rate swap agreements	9,291	9,291	4,370
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability for interest rate swap agreements	0	0	0
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability for interest rate swap agreements	9,291	9,291	$ 4,370
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability for interest rate swap agreements	$ 0	$ 0