Long-Term Debt - Components Table (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Apr. 04, 2017	Dec. 31, 2016	Jul. 28, 2014	Nov. 19, 2013
Long-Term Debt
Long-term debt	$ 973,339		$ 502,539
Revolving Credit Facility [Member]
Long-Term Debt
Long-term debt	$ 184,234		$ 14,100
Weighted average interest rate, as a percent	2.90%		4.00%
Senior Notes 5.125 Percent Due 2022
Long-Term Debt
Long-term debt	$ 247,701		$ 247,371
Interest rate, as a percentage	5.125%		5.125%
Aggregate principle amount	$ 250,000			$ 250,000
Capitalized debt issuance costs	2,300		$ 2,600
Convertible Senior Notes 1.00 percent due 2020
Long-Term Debt
Long-term debt	$ 246,444		$ 241,068
Effective interest rate percentage					5.26%
Interest rate, as a percentage	1.00%		1.00%
Aggregate principle amount	$ 287,500				$ 287,500
Unamortized discount and capitalized debt issuance costs	41,056		$ 46,432
Senior Notes 5.50 Percent Due 2025
Long-Term Debt
Long-term debt	$ 294,960
Interest rate, as a percentage	5.50%	5.50%
Aggregate principle amount	$ 300,000	$ 300,000
Capitalized debt issuance costs	$ 5,000