Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting [Abstract]
Income from operations	$ 179,938	$ 295,374	$ 382,214	$ 524,654
Interest expense	(5,915)	(8,958)	(12,600)	(18,549)
Other income, net	8,181	22,058	10,826	31,154
Income before income taxes	$ 182,204	$ 308,474	$ 380,440	$ 537,259