Equity Arrangements - Additional Information (Detail) (USD $)	0 Months Ended		1 Months Ended		3 Months Ended		1 Months Ended	12 Months Ended	0 Months Ended
	Feb. 10, 2015	Oct. 31, 2014	Mar. 31, 2015	Dec. 31, 2013	Apr. 04, 2015	Mar. 29, 2014	Nov. 30, 2010	Dec. 28, 2013	Dec. 29, 2012	Nov. 10, 2010	Jan. 03, 2015
Stockholders Equity Note [Line Items]
Forward share purchase contract		$ 150,000,000	$ 350,000,000
Payments for Repurchase of Common Stock	326,100,000				348,000,000	19,400,000
Long-term debt, including current maturities					4,355,000,000						4,323,800,000
Debt Instrument Convertible Conversion Warrant Strike Price, Percentage Higher than Previous Price on November 1, 2010							60.00%
Call option, aggregate premium				9,700,000
Debt Instrument Convertible Conversion Warrant Strike Price, Percentage Higher than Previous Price on November 1, 2010											$ 0.4
Equity Forward Contracts, Net Settlement, Shares		1,603,822	3,645,510
Option Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value	911,077
Treasury Stock Acquired, Average Cost Per Share	$ 96.46				$ 112.84
Treasury Stock, Shares, Acquired	3,381,162
Convertible Preferred Stock [Member]
Stockholders Equity Note [Line Items]
Open option contracts written at fair value					146,900,000
Call Option [Member]
Stockholders Equity Note [Line Items]
Call option, aggregate premium							50,300,000
Call option, average price (in dollars per share)							$ 5.97	$ 2.77
Open option contracts written at fair value					15,600,000
Notes 2 Point 25 Percent due 2018 [Member]
Stockholders Equity Note [Line Items]
Long-term debt, including current maturities											345,000,000
Convertible notes payable due in 2018 (junior subordinated)
Stockholders Equity Note [Line Items]
Long-term debt, including current maturities							632,500,000
Convertible preferred units issued, per share							$ 100
Maximum [Member] | Call Option [Member]
Stockholders Equity Note [Line Items]
Debt Instrument Convertible Conversion Warrant Strike Price							$ 97.95		$ 95.26
Minimum [Member] | Call Option [Member]
Stockholders Equity Note [Line Items]
Debt Instrument Convertible Conversion Warrant Strike Price							$ 75
Call Options Term Of Maturity-1										5 years
Convertible Preferred Units
Stockholders Equity Note [Line Items]
Convertible preferred units issued							6,325,000
Stated interest rate							4.75%
Convertible preferred stock, conversion rate					1.3709		1.3333
Conversion price of convertible note (in dollars per share)					$ 72.94		$ 75.00
Common stock to be issued up on conversion							8,433,123	3,500,000.0
Convertible Preferred Units | On or after December 22, 2015
Stockholders Equity Note [Line Items]
Convertible preferred stock, redemption price as a percent of liquidation preference							100.00%
Convertible Preferred Units | Maximum [Member]
Stockholders Equity Note [Line Items]
Convertible preferred stock, conversion rate											1.2399
Common Stock [Member]
Stockholders Equity Note [Line Items]
Conversion price of convertible note (in dollars per share)					$ 98.73
Common Stock [Member] | Maximum [Member]
Stockholders Equity Note [Line Items]
Payments for Repurchase of Common Stock								80.65
Common Stock [Member] | Minimum [Member]
Stockholders Equity Note [Line Items]
Payments for Repurchase of Common Stock								98.80
Call Option [Member]
Stockholders Equity Note [Line Items]
Number of common shares purchased under call option	9,100,000.0							12,200,000.0
Option Indexed to Issuer's Equity, Premium Amount								73,500,000
Option Indexed to Issuer's Equity, Average Premium Price Per Share								$ 6.03
Option Indexed to Issuer's Equity, Average Lower Strike Price					$ 86.01			$ 86.07
Option Indexed to Issuer's Equity, Average Upper Strike Price					$ 106.49			$ 106.56
Option Indexed to Issuer's Equity, Aggregate Fair Value					$ 28,300,000
Employee Stock Purchase Plans [Member] | Investment Type [Member]
Stockholders Equity Note [Line Items]
Debt Instrument, Number of Shares of Convertible Preferred Stock to be Delivered, As a Percentage of Purchase Contracts					85.00%