Stock-Based Compensation Plans (Summary of Stock Option Activity) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding at Beginning of Year	8,861	7,555	6,805
Shares, Granted	2,731	2,641	2,462
Shares, Exercised	(2,225)	(689)	(1,497)
Shares, Forfeited	(367)	(646)	(215)
Shares, Outstanding at End of Year	9,000	8,861	7,555
Shares, Exercisable at End of Year	2,745	3,003	2,024
Wtd. Avg. Ex. Price, Outstanding at Beginning of Year (usd per share)	$ 21	$ 21	$ 17
Wtd. Avg. Ex. Price, Granted (usd per share)	$ 25	$ 20	$ 29
Wtd. Avg. Ex. Price, Exercised (usd per share)	$ 16	$ 15	$ 16
Wtd. Avg. Ex. Price, Forfeited (usd per share)	$ 23	$ 21	$ 19
Wtd. Avg. Ex. Price, Outstanding at End of Year (usd per share)	$ 23	$ 21	$ 21
Wtd. Avg. Ex. Price, Exercisable at End of Year (usd per share)	$ 23	$ 19	$ 17
Wtd. Avg. Remaining Contract Life, Outstanding at End of Year	3 years 4 months 24 days	3 years 4 months 24 days	3 years 6 months
Wtd. Avg. Remaining Contract Life, Exercisable at End of Year	2 years 3 months 18 days	2 years 2 months 12 days	2 years 3 months 18 days
Aggregate Intrinsic Value, Exercised	$ 20,884	$ 3,810	$ 20,659
Aggregate Intrinsic Value, Outstanding at End of Year	85,633	11,730	66,295
Aggregate Intrinsic Value, Exercisable at End of Year	28,302	7,617	26,218
Non-Employee Director Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding at Beginning of Year	234	192	244
Shares, Granted	42	42	42
Shares, Exercised	(45)	0	(94)
Shares, Forfeited	0	0	0
Shares, Outstanding at End of Year	231	234	192
Shares, Exercisable at End of Year	231	234	192
Wtd. Avg. Ex. Price, Outstanding at Beginning of Year (usd per share)	$ 21	$ 21	$ 18
Wtd. Avg. Ex. Price, Granted (usd per share)	$ 25	$ 22	$ 32
Wtd. Avg. Ex. Price, Exercised (usd per share)	$ 20	$ 0	$ 17
Wtd. Avg. Ex. Price, Forfeited (usd per share)	$ 0	$ 0	$ 0
Wtd. Avg. Ex. Price, Outstanding at End of Year (usd per share)	$ 22	$ 21	$ 21
Wtd. Avg. Ex. Price, Exercisable at End of Year (usd per share)	$ 22	$ 21	$ 21
Wtd. Avg. Remaining Contract Life, Outstanding at End of Year	6 years 4 months 24 days	6 years 4 months 24 days	6 years 9 months 18 days
Wtd. Avg. Remaining Contract Life, Exercisable at End of Year	6 years 4 months 24 days	6 years 4 months 24 days	6 years 9 months 18 days
Aggregate Intrinsic Value, Exercised	300		1,362
Aggregate Intrinsic Value, Outstanding at End of Year	2,491	225	1,740
Aggregate Intrinsic Value, Exercisable at End of Year	$ 2,491	$ 225	$ 1,740