Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 122,840	$ 154,073
Marketable securities	249,858	299,849
Accounts receivable, net of allowance for bad debts	189,381	168,620
Prepaid expenses and other current assets	170,232	163,396
Assets held for sale	491
Total current assets	732,802	785,938
Drilling and other property and equipment, net of accumulated depreciation	5,170,858	5,184,222
Other assets	208,824	65,534
Total assets	6,112,484	6,035,694
Current liabilities:
Accounts payable	60,284	43,933
Accrued liabilities	197,877	172,228
Taxes payable	15,096	20,685
Total current liabilities	273,257	236,846
Long-term debt	1,974,365	1,973,922
Deferred tax liability	97,810	104,380
Other liabilities	255,176	135,893
Total liabilities	2,600,608	2,451,041
Commitments and contingencies (Note 8)
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; 144,606,992 shares issued and 137,580,203 shares outstanding at March 31, 2019; 144,383,662 shares issued and 137,438,353 shares outstanding at December 31, 2018)	1,446	1,444
Additional paid-in capital	2,019,555	2,018,143
Retained earnings	1,696,087	1,769,415
Accumulated other comprehensive gain	2	21
Treasury stock, at cost (7,026,789 and 6,945,309 shares of common stock at March 31, 2019 and December 31, 2018, respectively)	(205,214)	(204,370)
Total stockholders’ equity	3,511,876	3,584,653
Total liabilities and stockholders’ equity	$ 6,112,484	$ 6,035,694