Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 128,928	$ 119,028
Marketable securities	5,067	11,518
Accounts receivable, net of allowance for bad debts	363,597	405,370
Prepaid expenses and other current assets	110,842	119,479
Assets held for sale	6,600	14,200
Total current assets	615,034	669,595
Drilling and other property and equipment, net of accumulated depreciation	6,219,242	6,378,814
Other assets	110,323	101,485
Total assets	6,944,599	7,149,894
Current liabilities:
Accounts payable	51,421	70,272
Accrued liabilities	289,209	253,769
Taxes payable	40,357	15,093
Short-term borrowings		286,589
Total current liabilities	380,987	625,723
Long-term debt	1,980,049	1,979,778
Deferred tax liability	230,332	276,529
Other liabilities	158,451	155,094
Total liabilities	$ 2,749,819	$ 3,037,124
Commitments and contingencies (Note 10)
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; 143,997,757 shares issued and 137,169,663 shares outstanding at March 31, 2016; 143,978,877 shares issued and 137,158,706 shares outstanding at December 31, 2015)	$ 1,440	$ 1,440
Additional paid-in capital	2,000,828	1,999,634
Retained earnings	2,406,693	2,319,136
Accumulated other comprehensive gain (loss)	(11,595)	(5,035)
Treasury stock, at cost (6,828,094 and 6,820,171 shares of common stock at March 31, 2016 and December 31, 2015, respectively)	(202,586)	(202,405)
Total stockholders' equity	4,194,780	4,112,770
Total liabilities and stockholders' equity	$ 6,944,599	$ 7,149,894