Significant Accounting Policies (Details 5) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Changes in accumulated other comprehensive income (loss)
Balance at beginning of period	$ 5,093,177
Balance at end of period	4,442,881
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Balance at beginning of period	(61,041)
Other comprehensive (loss) before reclassifications	(121,370)
Amounts reclassified from accumulated other comprehensive income (loss)	(64,164)
Net current-period other comprehensive income (loss)	(185,534)
Balance at end of period	(246,575)
Currency translation adjustments
Changes in accumulated other comprehensive income (loss)
Balance at beginning of period	(110,722)
Other comprehensive (loss) before reclassifications	(119,129)
Net current-period other comprehensive income (loss)	(119,129)
Balance at end of period	(229,851)
Accumulated derivative losses, net
Changes in accumulated other comprehensive income (loss)
Balance at beginning of period	(39,161)
Other comprehensive (loss) before reclassifications	16,479
Amounts reclassified from accumulated other comprehensive income (loss)	4,521
Net current-period other comprehensive income (loss)	21,000
Balance at end of period	(18,161)
Net gains (losses) on marketable securities
Changes in accumulated other comprehensive income (loss)
Balance at beginning of period	88,842
Other comprehensive (loss) before reclassifications	(18,720)
Amounts reclassified from accumulated other comprehensive income (loss)	(68,685)
Net current-period other comprehensive income (loss)	(87,405)
Balance at end of period	$ 1,437