Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 752,207	$ 844,611	$ 733,993
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted Average Number of Shares Outstanding, Basic	202,681	216,305	222,475
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	1,005	1,401	1,596
Weighted Average Number of Shares Outstanding, Diluted	203,686	217,706	224,071
Basic (in dollars per share)	$ 3.71	$ 3.90	$ 3.30
Diluted (in dollars per share)	$ 3.69	$ 3.88	$ 3.28