Stock-Based Compensation (Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Number of options (in shares):
Options outstanding beginning of the year (in shares) | shares	444,278
Exercised (in shares) | shares	(178,017)
Forfeited or expired (in shares) | shares	(3,979)
Options outstanding end of the year (in shares) | shares	262,282
Weighted Average Exercise Price (in dollars per share):
Options outstanding beginning of the year (in dollars per share) | $ / shares	$ 43.56
Exercised (in dollars per share) | $ / shares	45.07
Forfeited or expired (in dollars per share) | $ / shares	44.72
Options outstanding end of the year (in dollars per share) | $ / shares	$ 42.52
Outstanding, Intrinsic Value | $	$ 10