Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 278,889	$ 154,030
Marketable investments	409,645	325,175
Accounts receivable, net of allowance of none for 2013 and 2012	126,297	116,626
Other current assets	46,424	35,385
Inventories, net	47,758	37,254
Total current assets	909,013	668,470
Marketable investments	448,134	305,726
Marketable investments and cash-restricted	5,369	5,377
Goodwill and other intangible assets, net	14,115	16,408
Property, plant, and equipment, net	464,950	453,685
Deferred tax assets, net	192,718	150,147
Other assets	53,268	26,782
Total assets	2,087,567	1,626,595
Current liabilities:
Accounts payable and accrued expenses	92,244	83,188
Convertible notes	215,845
Share Tracking Award Plans	287,956	75,412
Mortgages payable-current	66,613	1,291
Other current liabilities	25,016	16,864
Total current liabilities	687,674	176,755
Non-current liabilities:
Convertible notes		204,667
Mortgages payable	3,724	70,343
Other liabilities	91,858	79,967
Total liabilities	783,256	531,732
Commitments and contingencies:
Temporary equity	45,037	10,882
Stockholders' equity:
Common stock, par value $.01, 245,000,000 shares authorized, 63,013,192 and 62,082,007 shares issued, and 50,388,140 and 50,165,953 shares outstanding at December 31, 2013 and 2012, respectively	630	621
Additional paid-in capital	1,057,224	1,015,835
Accumulated other comprehensive loss	(13,183)	(14,957)
Treasury stock at cost, 12,625,052 and 11,916,054 shares at December 31, 2013 and 2012, respectively	(513,437)	(470,998)
Retained earnings	728,040	553,480
Total stockholders' equity	1,259,274	1,083,981
Total liabilities and stockholders' equity	2,087,567	1,626,595
Preferred stock
Stockholders' equity:
Preferred stock
Series A junior participating preferred stock
Stockholders' equity:
Preferred stock