Stockholder's Equity (Details 5) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	$ 14,925,452	$ 15,281,472
OCI, before reclassifications, net of tax	(21,166)	5,907
Balances at end of period	14,800,487	15,313,523
Accumulated Foreign Currency Adjustment Attributable to Parent
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	(110,581)	(173,496)
OCI, before reclassifications, net of tax	(21,166)	22,384
Balances at end of period	(131,747)	(151,112)
Accumulated Net Investment Gain (Loss) Attributable to Parent
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	0	5,120
OCI, before reclassifications, net of tax	0	(16,477)
Balances at end of period	0	(11,357)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	(884)	(1,153)
OCI, before reclassifications, net of tax	0	0
Balances at end of period	(884)	(1,153)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	0	(2)
OCI, before reclassifications, net of tax	0	0
Balances at end of period	0	(2)
Accumulated Other Comprehensive Income (Loss)
Summary of accumulated other comprehensive income/(loss) [Line Items]
Balances at beginning of period	(111,465)	(169,531)
Balances at end of period	$ (132,631)	$ (163,624)