Long-Term Indebtedness (Details 2) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Summary of Long-term debt
Net discount	$ (8,803)	$ (2,192)
Deferred financing costs	(3,589)	(4,188)
Long-term debt and Short-term borrowings	2,048,057	1,653,647
Less current portion	(28,867)	(29,161)
Total long-term debt	2,019,190	1,624,486
Amended and Restated Term Loan B [Member]
Summary of Long-term debt
Long-term debt	544,750	544,750
Senior Unsecured 2021 Notes [Member]
Summary of Long-term debt
Long-term debt	0	800,000
Senior Unsecured 2024 Notes [Member]
Summary of Long-term debt
Long-term debt	1,000,000	300,000
Senior Unsecured 2027 Notes [Member]
Summary of Long-term debt
Long-term debt	500,000	0
HWP Refinance Loan [Member]
Summary of Long-term debt
Long-term debt	28,867	29,161
Amended and Restated Term Loan B, Senior Unsecured 2021 and Senior Unsecured 2024 Notes [Member]
Summary of Long-term debt
Deferred financing costs		$ (18,072)
Amended and Restated Term Loan B, Senior Unsecured 2024 Notes and 2027 Notes [Member]
Summary of Long-term debt
Deferred financing costs	$ (16,757)