Equity Incentive Plans (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity Incentive Plans
Compensation expense	$ 80,000	$ 81,000	$ 88,000
Share-based compensation arrangement by share-based payment award, recognized tax benefits	28,000	28,000	30,000
Cash received from the exercise of options	187,000	187,000	314,000
Tax benefit realized on options exercised and stock unrestricted	61,000	82,000	73,000
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	$ 62,000
Common stock authorized for stock-based awards (in shares)	97,600
Common stock reserved for further issuance (in shares)	21,700
Weighted average grant date fair value
Tax (expense) benefit realized related to all stock-based compensation included in shareholder's equity	$ 30,000	$ 46,000	$ 32,000
Stock options
Equity Incentive Plans
Vesting period of options granted prior to 2010	3 years
Portion of awards vesting and unrestricting on second anniversary of grant date (as a percent)	50.00%
Portion of awards vesting and unrestricting on third and fourth anniversaries of grant date (as a percent)	25.00%
Expiration term for options	10 years
Assumptions used to determine fair value of options granted
Weighted average expected term	5 years	6 years 6 months	6 years 6 months
Expected volatility, low end of the range (as a percent)	16.00%	16.00%	16.80%
Expected volatility, high end of the range (as a percent)	34.30%	37.80%	42.20%
Weighted average volatility (as a percent)	24.30%	24.70%	28.30%
Expected dividends, minimum range (as a percent)	1.90%	1.60%	1.70%
Expected dividends, maximum range (as a percent)	2.10%	2.10%	2.20%
Weighted average expected dividends (as a percent)	2.10%	1.70%	2.10%
Risk-free rate, low end of the range (as a percent)	0.20%	0.00%	0.00%
Risk-free rate, high end of the range (as a percent)	2.40%	2.40%	3.00%
Stock option activity
Outstanding at the beginning of the period (in shares)	15,716
Granted (in shares)	3,013
Exercised (in shares)	(4,755)
Forfeited (in shares)	(378)
Expired (in shares)	(36)
Outstanding at the end of the period (in shares)	13,560	15,716
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at the beginning of the period (in dollars per share)	$ 45.81
Granted (in dollars per share)	62.84
Exercised (in dollars per share)	43.20
Forfeited (in dollars per share)	61.64
Expired (in dollars per share)	64.83
Outstanding at the end of the period (in dollars per share)	$ 50.01	$ 45.81
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Aggregate intrinsic value, Outstanding	$ 326,911
Aggregate intrinsic value, net of expected forfeitures, outstanding	325,668
Aggregate intrinsic value, exercisable ("vested"), outstanding	$ 258,367
Weighted average remaining contractual term, Outstanding	6 years
Weighted average remaining contractual term, net of expected forfeitures, outstanding	5 years 10 months 24 days
Weighted average remaining contractual term, exercisable ("vested"), outstanding	4 years 6 months
Outstanding, net of expected forfeitures (in shares)	13,434
Outstanding, exercisable ("vested") (in shares)	8,104
Outstanding, net of expected forfeitures (in dollars per share)	$ 49.88
Outstanding, exercisable ("vested") (in dollars per share)	42.24
Weighted average grant date fair value of options granted (in dollars per share)	$ 12.25	$ 15.45	$ 12.50
Intrinsic value of options exercised	$ 119,000	$ 117,000	$ 151,000
Weighted average grant date fair value
Tax (expense) benefit realized related to all stock-based compensation included in shareholder's equity	23,000	$ 23,000	$ 23,000
Nonqualified stock options
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	$ 25,000
Expected period of recognition of unrecognized compensation cost	1 year 8 months 19 days
Restricted stock units
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	$ 25,000
Expected period of recognition of unrecognized compensation cost	1 year 9 months 15 days
Portion of awards vesting and unrestricting on second anniversary of grant date (as a percent)	50.00%
Portion of awards vesting and unrestricting on third and fourth anniversaries of grant date (as a percent)	25.00%
Stock units activity
Outstanding at the beginning of the period (in shares)	1,839
Granted (in shares)	360
Vested (in shares)	(449)
Forfeited (in shares)	(71)
Outstanding at the end of the period (in shares)	1,679	1,839
Weighted average grant date fair value
Weighted average grant date fair value, nonvested at the beginning of the period (in dollars per share)	$ 52.86
Weighted average grant date fair value, granted (in dollars per share)	63.51	$ 69.25	$ 52.70
Weighted average grant date fair value, vested (in dollars per share)	39.30
Weighted average grant date fair value, forfeited (in dollars per share)	59.51
Weighted average grant date fair value, nonvested at the end of the period (in dollars per share)	$ 58.49	$ 52.86
Total fair value of restricted stock and restricted stock units vested	$ 29,000	$ 63,000	$ 60,000
Performance stock awards
Equity Incentive Plans
Unrecognized compensation cost related to nonvested awards	$ 12,000
Expected period of recognition of unrecognized compensation cost	1 year 8 months 5 days
Stock units activity
Outstanding at the beginning of the period (in shares)	930
Granted (in shares)	520
Vested (in shares)	(442)
Adjustment for performance achievement (in shares)	(15)
Forfeited (in shares)	(74)
Outstanding at the end of the period (in shares)	919	930
Weighted average grant date fair value
Weighted average grant date fair value, nonvested at the beginning of the period (in dollars per share)	$ 53.27
Weighted average grant date fair value, granted (in dollars per share)	62.32	$ 70.37	$ 52.18
Weighted average grant date fair value, adjustment for performance achievement (in dollars per share)	45.61
Weighted average grant date fair value, vested (in dollars per share)	45.61
Weighted average grant date fair value, forfeited (in dollars per share)	61.87
Weighted average grant date fair value, nonvested at the end of the period (in dollars per share)	$ 61.50	$ 53.27
Total fair value of restricted stock and restricted stock units vested	$ 28,000	$ 56,000