Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Mar. 25, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 18, 2016	Oct. 02, 2014	Feb. 04, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation cost										$ 148,200,000	$ 168,900,000	$ 146,000,000
Tax benefit from share-based compensation expense										$ 53,700,000	$ 60,700,000	52,600,000
Employee stock purchase plan, purchase price per share as a percent of closing price										95.00%
Increase in stock repurchase program authorization														$ 5,000,000,000.0
Accelerated share repurchase program, shares repurchased										10.4	30.4
Outstanding principal amount		$ 513,400,000								$ 513,400,000
Dividends Payable, Date to be Paid		Dec. 21, 2015	Sep. 25, 2015	Jun. 25, 2015	Mar. 25, 2015	Dec. 22, 2014	Sep. 25, 2014	Jun. 25, 2014	Mar. 25, 2014
Dividends Payable, Date of Record		Dec. 04, 2015	Sep. 10, 2015	Jun. 10, 2015	Mar. 10, 2015	Dec. 05, 2014	Sep. 10, 2014	Jun. 10, 2014	Mar. 10, 2014
Incentive Compensation Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of registered shares for issuance		60.1								60.1
Number of shares available for future issuance		18.7								18.7
Restricted Stock Units (RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Fair value of shares vested										$ 257,200,000	$ 174,000,000	46,700,000
Approximate number of performance restricted stock units granted										0.4
Unrecognized compensation cost		$ 98,700,000								$ 98,700,000
Weighted-average remaining requisite service period										10 months
Stock Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock incentive plan vesting period, years										3 years
Stock option term, years										10 years
Intrinsic value of options exercised										$ 188,100,000	156,700,000	176,000,000
Tax benefit from stock option exercises and disqualifying dispositions										68,000,000	53,200,000	56,800,000
Cash received from exercise of stock options										162,200,000	$ 283,600,000	$ 524,700,000
Unrecognized compensation cost		$ 19,300,000								$ 19,300,000
Weighted-average remaining requisite service period										10 months
Subsequent Event [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Dividends Payable, Amount Per Share													$ 0.6500
Dividends Payable, Date to be Paid	Mar. 25, 2016
Dividends Payable, Date of Record	Mar. 10, 2016
Employee Stock Purchase Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of registered shares for issuance		14.0								14.0
Number of shares available for future issuance		5.8								5.8
Maximum amount of stock employees are permitted to purchase per calender year (whole dollars)										$ 25,000
Payroll deductions, percent of gross compensation, minimum		1.00%								1.00%
Payroll deductions, percent of gross compensation, maximum		15.00%								15.00%
Employee stock purchase plan, purchase price per share as a percent of closing price										95.00%
Stock Issued During Period, Shares										0.1
Call Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of shares subject to purchase call options												3.0
Aggregate premium paid												$ 25,800,000
Call Option [Member] | Minimum [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Average price per share												$ 77.50
Call Option [Member] | Maximum [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Average price per share												$ 83.10
Shareholders' Equity [Member] | Call Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Aggregate premium paid												$ 7,900,000
Derivative assets [Member] | Call Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Aggregate premium paid												17,900,000
Aggregate fair value												$ 27,500,000
Repurchase Agreements [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Accelerated share repurchase program, amount authorized															$ 600,000,000.0
Accelerated share repurchase program, shares repurchased											6.6
Equity Unit Purchase Agreements [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity Units Issued										25.0
Outstanding principal amount		$ 1,250,000,000								$ 1,250,000,000
Put Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Accelerated share repurchase program, shares repurchased										0.7
Average price per share			$ 143.89
Option Indexed to Issuer's Equity, Shares										5.3
Options Expired Unexercised										4.6
Call Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Accelerated share repurchase program, shares repurchased										2.1
Average price per share		$ 135.03								$ 135.03