Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 147,509	$ 154,073
Marketable securities	149,945	299,849
Accounts receivable, net of allowance for bad debts	163,086	168,620
Prepaid expenses and other current assets	130,124	163,396
Total current assets	590,664	785,938
Drilling and other property and equipment, net of accumulated depreciation	5,163,696	5,184,222
Other assets	222,876	65,534
Total assets	5,977,236	6,035,694
Current liabilities:
Accounts payable	60,533	43,933
Accrued liabilities	192,194	172,228
Taxes payable	16,722	20,685
Total current liabilities	269,449	236,846
Long-term debt	1,974,816	1,973,922
Deferred tax liability	74,281	104,380
Other liabilities	259,793	135,893
Total liabilities	2,578,339	2,451,041
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock (par value $0.01, 25,000,000 shares authorized, none issued and outstanding)
Common stock (par value $0.01, 500,000,000 shares authorized; 144,764,125 shares issued and 137,690,627 shares outstanding at June 30, 2019; 144,383,662 shares issued and 137,438,353 shares outstanding at December 31, 2018)	1,448	1,444
Additional paid-in capital	2,021,095	2,018,143
Retained earnings	1,582,099	1,769,415
Accumulated other comprehensive (loss) gain	(6)	21
Treasury stock, at cost (7,073,498 and 6,945,309 shares of common stock at June 30, 2019 and December 31, 2018, respectively)	(205,739)	(204,370)
Total stockholders’ equity	3,398,897	3,584,653
Total liabilities and stockholders’ equity	$ 5,977,236	$ 6,035,694