Debt - Long-term debt, net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 1,070,000	$ 990,000
Debt issuance costs, net	(5,919)	(6,364)
Long-term debt, net	1,064,081	983,636
Senior Notes \| January 2022 Notes
Debt Instrument [Line Items]
Long-term debt	450,000	450,000
Debt issuance costs, net	(2,766)	(3,010)
Long-term debt, net	447,234	446,990
Senior Notes \| March 2023 Notes
Debt Instrument [Line Items]
Long-term debt	350,000	350,000
Debt issuance costs, net	(3,153)	(3,354)
Long-term debt, net	346,847	346,646
Secured debt \| Senior Secured Credit Facility
Debt Instrument [Line Items]
Long-term debt	270,000	190,000
Debt issuance costs, net	0	0
Long-term debt, net	270,000	190,000
Secured debt \| Senior Secured Credit Facility \| Other noncurrent assets, net
Debt Instrument [Line Items]
Debt issuance costs related to line of credit arrangements	$ 6,600	$ 7,000

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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