Statement of Cash Flows	9 Months Ended
Statement of Cash Flows	Sep. 30, 2012
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Statement of Cash Flows	Statement of Cash Flows Supplemental disclosure of non-cash investing and financing activities: Included in accounts payable and accrued expenses at September 30, 2012 and December 31, 2011 were $7.0 million and $6.2 million, respectively, of accrued capital expenditures. Included in accounts payable and accrued expenses at September 30, 2011 and December 31, 2010 were $4.9 million and $10.7 million, respectively, of accrued capital expenditures. In addition, during the nine months ended September 30, 2012, the Company incurred non-cash charges of $2.7 million in connection with disposals and retirements of fixed assets. Included in marketable securities at September 30, 2012 and December 31, 2011 were $1.7 million and $0.7 million, respectively, of accrued interest income. Included in marketable securities at September 30, 2011 and December 31, 2010 were $1.1 million and $1.4 million, respectively, of accrued interest income.

The entire disclosure for supplemental cash flow activities, including cash, noncash, and part noncash transactions, for the period. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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