Supplemental Balance Sheet, Income Statement and Cash Flow Information (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ 216,140	$ 340,143
Other comprehensive income (loss) before reclassifications	(142,424)	(39,529)
Amount reclassified from accumulated other comprehensive income (loss)	3,806	(84,474)
Net other comprehensive income (loss)	(138,618)	(124,003)	110,331
Balance at the end of the period	77,522	216,140	340,143
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(2,419)	(2,793)
Amount reclassified from accumulated other comprehensive income (loss)	375	374
Net other comprehensive income (loss)	375	374
Balance at the end of the period	(2,044)	(2,419)
Unrealized gains (losses) on available-for-sale securities
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	71,742	134,229
Other comprehensive income (loss) before reclassifications	(59,991)	22,968
Amount reclassified from accumulated other comprehensive income (loss)	3,245	(85,455)
Net other comprehensive income (loss)	(56,746)	(62,487)
Balance at the end of the period	14,996	71,742
Accumulated Defined Benefit Plans Adjustment
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(4,075)	(7,632)
Other comprehensive income (loss) before reclassifications	(3,374)	2,950
Amount reclassified from accumulated other comprehensive income (loss)	186	607
Net other comprehensive income (loss)	(3,188)	3,557
Balance at the end of the period	(7,263)	(4,075)
Accumulated Translation Adjustment
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	150,892	216,339
Other comprehensive income (loss) before reclassifications	(79,059)	(65,447)
Net other comprehensive income (loss)	(79,059)	(65,447)
Balance at the end of the period	$ 71,833	$ 150,892