Description of Business and Basis of Presentation (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in accounts receivable	$ (32,784)	$ (66,778)
Increase in accounts payable and accrued liabilities	(130,100)	(88,567)
Cash used for purchases of available-for-sale securities	106,431	613,429
Cash provided by proceeds from sales/maturities of available-for-sale securities	$ 111,993	592,799
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in accounts receivable			$ 23,000
Increase in accounts payable and accrued liabilities			14,000
Increase in other noncurrent liabilities			$ 9,000
Cash used for purchases of available-for-sale securities		422,000
Cash provided by proceeds from sales/maturities of available-for-sale securities		$ 422,000