CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 304,251	$ 42,828
Accounts receivable, net of allowance for doubtful accounts of $2,296 and $2,323 at March 31, 2018 and December 31, 2017, respectively	596,888	580,354
Federal and state income taxes receivable	1,128	1,152
Inventory	72,069	69,167
Other	64,639	53,354
Total current assets	1,038,975	746,855
Property and equipment, net	4,217,049	4,254,730
Goodwill and intangible assets	689,398	687,072
Deposits on equipment purchases	18,645	16,351
Deferred tax assets, net	1,007	3,875
Other	50,650	49,973
Total assets	6,015,724	5,758,856
Current liabilities:
Accounts payable	359,582	319,621
Accrued expenses	241,904	226,629
Total current liabilities	601,486	546,250
Borrowings under revolving credit facility		268,000
Long-term debt, net of debt discount and issuance costs of $6,164 and $1,217 at March 31, 2018 and December 31, 2017, respectively	1,118,836	598,783
Deferred tax liabilities, net	348,250	350,836
Other	12,611	12,494
Total liabilities	2,081,183	1,776,363
Commitments and contingencies (see Note 9)
Stockholders' equity:
Preferred stock, par value $.01; authorized 1,000,000 shares, no shares issued
Common stock, par value $.01; authorized 300,000,000 shares with 266,298,983 and 266,259,083 issued and 221,571,572 and 222,456,472 outstanding at March 31, 2018 and December 31, 2017, respectively	2,663	2,662
Additional paid-in capital	2,795,672	2,785,823
Retained earnings	2,067,007	2,105,897
Accumulated other comprehensive income	4,838	6,822
Treasury stock, at cost, 44,727,411 and 43,802,611 shares at March 31, 2018 and December 31, 2017, respectively	(935,639)	(918,711)
Total stockholders' equity	3,934,541	3,982,493
Total liabilities and stockholders' equity	$ 6,015,724	$ 5,758,856

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.