Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Long-term debt	$ 1,660,636	$ 1,553,389
Debt issuance costs	$ 5,782	$ 6,641
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	93,884,971	93,400,929
Treasury stock, shares	15,790,463	10,174,589
Revolving Credit Facility [Member]
Long-term debt	$ 145,000	$ 30,000