Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 461,301	$ 790,078
Marketable securities	239,388	124,873
Accounts receivable, net	428,457	400,159
Inventories	471,879	399,298
Prepaid expenses and other current assets	13,888	14,700
Deferred income taxes	34,169	22,305
Total current assets	1,649,082	1,751,413
Property, plant and equipment, net	2,088,014	1,510,048
Equity investments	66,875	43,736
Other assets, net
Intangible assets, net	159,046	48,292
Deferred charges and other assets, net	97,892	58,707
Total other assets, net	256,938	106,999
Total assets	4,060,909	3,412,196
Current liabilities
Accounts payable, current	249,613	217,050
Accrued liabilities	155,245	181,460
Total current liabilities	404,858	398,510
Long-term debt	763,879	763,761
Deferred income taxes	437,976	326,290
Other liabilities	35,593	51,379
Total liabilities	1,642,306	1,539,940
Commitments and contingencies (Notes 7 and 18)
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value, 150,000,000 shares authorized; 67,187,224 and 66,601,909 shares issued at December 31, 2012 and 2011, respectively	673	672
Common stock, held in treasury, at cost; 284,493 and 69,816 shares at December 31, 2012 and 2011, respectively	(46,220)	(13,302)
Additional paid-in capital	512,105	496,254
Retained earnings	1,954,661	1,399,472
Accumulated other comprehensive loss	(2,616)	(10,840)
Total stockholders' equity	2,418,603	1,872,256
Total liabilities and stockholders' equity	$ 4,060,909	$ 3,412,196