Summary of Significant Accounting Policies - Condensed Consolidated Balance Sheet (Details) $ / shares in Units, $ in Millions	Apr. 02, 2016 USD ($) $ / shares shares	Apr. 02, 2016 € / shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2015 € / shares	Mar. 28, 2015 USD ($)	Dec. 27, 2014 USD ($)
Assets
Cash and cash equivalents	$ 588.9		$ 417.8		$ 3,430.4	$ 3,596.1
Accounts receivable, net of allowance for doubtful accounts of $4.3 million, and $4.5 million, respectively	1,188.0		1,189.0
Inventories	905.1		898.7
Prepaid expenses and other current assets	332.6		286.1
Total current assets	3,014.6		2,791.6
Property, plant and equipment, net	896.3		886.2
Tysabri® royalty stream - at fair value	5,020.0		5,310.0
Goodwill and other indefinite-lived intangible assets	6,873.6		7,069.0
Other intangible assets, net	3,374.8		2,973.1
Non-current deferred income taxes	86.8		71.4
Other non-current assets	233.6		248.3
Total non-current assets	16,485.1		16,558.0
Total assets	19,499.7		19,349.6		19,349.6
Allowance for doubtful accounts	4.3		4.5
Liabilities and Shareholders’ Equity
Accounts payable	557.2		555.8
Payroll and related taxes	92.2		125.3
Accrued customer programs	316.7		396.0
Accrued liabilities	343.2		351.9
Accrued income taxes	262.4		62.7
Current indebtedness	650.7		1,060.5
Total current liabilities	2,222.4		2,552.2
Long-term debt, less current portion	5,902.7		4,971.6
Non-current deferred income taxes	(1,240.7)		(1,372.7)
Other non-current liabilities	408.5		346.3
Total non-current liabilities	7,551.9		6,690.6
Total liabilities	9,774.3		9,242.8
Commitments and contingencies - Note 14
Shareholders’ equity
Preferred shares, $0.0001 par value, 10 million shares authorized	0.0		0.0
Ordinary shares, €0.001 par value, 10 billion shares authorized	8,160.8		8,142.6
Accumulated other comprehensive income (loss)	137.4		(15.3)
Retained earnings	1,427.8		1,980.1
Total controlling interest	9,726.0		10,107.4
Noncontrolling interest	(0.6)		(0.6)
Total shareholders’ equity	9,725.4		10,106.8
Total liabilities and shareholders' equity	$ 19,499.7		$ 19,349.6
Preferred shares, par value (in usd per share) | $ / shares	$ 0.0001		$ 0.0001
Preferred shares, authorized (in shares) | shares	10,000,000		10,000,000
Ordinary shares, par value (in dollars per share) | € / shares		€ 0.001		€ 0.001
Ordinary shares, authorized (in shares) | shares	10,000,000,000		10,000,000,000
Previously Reported
Assets
Cash and cash equivalents	$ 588.9		$ 417.8		3,430.4	3,596.1
Accounts receivable, net of allowance for doubtful accounts of $4.3 million, and $4.5 million, respectively	1,184.2		1,193.1
Inventories	868.8		844.4
Prepaid expenses and other current assets	332.6		289.1
Total current assets	2,974.5		2,744.4
Property, plant and equipment, net	896.3		886.2
Tysabri® royalty stream - at fair value	0.0		0.0
Goodwill and other indefinite-lived intangible assets	7,033.0		7,281.2
Other intangible assets, net	8,519.1		8,190.5
Non-current deferred income taxes	78.0		54.6
Other non-current assets	225.3		237.0
Total non-current assets	16,751.7		16,649.5
Total assets	19,726.2		19,393.9
Allowance for doubtful accounts	4.3		4.5
Liabilities and Shareholders’ Equity
Accounts payable	559.9		554.9
Payroll and related taxes	92.2		125.3
Accrued customer programs	331.0		398.0
Accrued liabilities	307.5		308.4
Accrued income taxes	179.4		85.2
Current indebtedness	619.2		1,018.3
Total current liabilities	2,089.2		2,490.1
Long-term debt, less current portion	5,902.7		4,971.6
Non-current deferred income taxes	(1,487.0)		(1,563.7)
Other non-current liabilities	400.6		332.4
Total non-current liabilities	7,790.3		6,867.7
Total liabilities	9,879.5		9,357.8
Commitments and contingencies - Note 14
Shareholders’ equity
Preferred shares, $0.0001 par value, 10 million shares authorized	0.0		0.0
Ordinary shares, €0.001 par value, 10 billion shares authorized	8,160.8		8,144.6
Accumulated other comprehensive income (loss)	136.7		(15.5)
Retained earnings	1,549.8		1,907.6
Total controlling interest	9,847.3		10,036.7
Noncontrolling interest	(0.6)		(0.6)
Total shareholders’ equity	9,846.7		10,036.1
Total liabilities and shareholders' equity	$ 19,726.2		$ 19,393.9
Preferred shares, par value (in usd per share) | $ / shares			$ 0.0001
Preferred shares, authorized (in shares) | shares			10,000,000
Ordinary shares, par value (in dollars per share) | € / shares		€ 0.001		€ 0.001
Ordinary shares, authorized (in shares) | shares	10,000,000,000		10,000,000,000
Adjustments | Tysabri®
Assets
Cash and cash equivalents	$ 0.0		$ 0.0		0.0	0.0
Accounts receivable, net of allowance for doubtful accounts of $4.3 million, and $4.5 million, respectively	0.0		0.0
Inventories	0.0		0.0
Prepaid expenses and other current assets	0.0		0.0
Total current assets	0.0		0.0
Property, plant and equipment, net	0.0		0.0
Tysabri® royalty stream - at fair value	5,020.0		5,310.0
Goodwill and other indefinite-lived intangible assets	0.0		0.0
Other intangible assets, net	(5,139.7)		(5,212.2)
Non-current deferred income taxes	0.0		0.0
Other non-current assets	0.0		0.0
Total non-current assets	(119.7)		97.8
Total assets	(119.7)		97.8
Allowance for doubtful accounts	0.0		0.0
Liabilities and Shareholders’ Equity
Accounts payable	0.0		0.0
Payroll and related taxes	0.0		0.0
Accrued customer programs	0.0		0.0
Accrued liabilities	0.0		0.0
Accrued income taxes	0.0		0.0
Current indebtedness	0.0		0.0
Total current liabilities	0.0		0.0
Long-term debt, less current portion	0.0		0.0
Non-current deferred income taxes	15.0		(12.2)
Other non-current liabilities	0.0		0.0
Total non-current liabilities	(15.0)		12.2
Total liabilities	(15.0)		12.2
Shareholders’ equity
Preferred shares, $0.0001 par value, 10 million shares authorized	0.0		0.0
Ordinary shares, €0.001 par value, 10 billion shares authorized	0.0		0.0
Accumulated other comprehensive income (loss)	0.0		0.0
Retained earnings	(104.7)		85.6
Total controlling interest	(104.7)		85.6
Noncontrolling interest	0.0		0.0
Total shareholders’ equity	(104.7)		85.6
Total liabilities and shareholders' equity	(119.7)		97.8
Adjustments | Other
Assets
Cash and cash equivalents	0.0		0.0		$ 0.0	$ 0.0
Accounts receivable, net of allowance for doubtful accounts of $4.3 million, and $4.5 million, respectively	3.8		(4.1)
Inventories	36.3		54.3
Prepaid expenses and other current assets	0.0		(3.0)
Total current assets	40.1		47.2
Property, plant and equipment, net	0.0		0.0
Tysabri® royalty stream - at fair value	0.0		0.0
Goodwill and other indefinite-lived intangible assets	(159.4)		(212.2)
Other intangible assets, net	(4.6)		(5.2)
Non-current deferred income taxes	8.8		16.8
Other non-current assets	8.3		11.3
Total non-current assets	(146.9)		(189.3)
Total assets	(106.8)		(142.1)
Allowance for doubtful accounts	0.0		0.0
Liabilities and Shareholders’ Equity
Accounts payable	(2.7)		0.9
Payroll and related taxes	0.0		0.0
Accrued customer programs	(14.3)		(2.0)
Accrued liabilities	35.7		43.5
Accrued income taxes	83.0		(22.5)
Current indebtedness	31.5		42.2
Total current liabilities	133.2		62.1
Long-term debt, less current portion	0.0		0.0
Non-current deferred income taxes	231.3		203.2
Other non-current liabilities	7.9		13.9
Total non-current liabilities	(223.4)		(189.3)
Total liabilities	(90.2)		(127.2)
Shareholders’ equity
Preferred shares, $0.0001 par value, 10 million shares authorized	0.0		0.0
Ordinary shares, €0.001 par value, 10 billion shares authorized	0.0		(2.0)
Accumulated other comprehensive income (loss)	0.7		0.2
Retained earnings	(17.3)		(13.1)
Total controlling interest	(16.6)		(14.9)
Noncontrolling interest	0.0		0.0
Total shareholders’ equity	(16.6)		(14.9)
Total liabilities and shareholders' equity	(106.8)		(142.1)
Adjustments | BCH Deferred Tax Matters Misstatement
Assets
Goodwill and other indefinite-lived intangible assets	234.2		(223.3)
Non-current deferred income taxes	284.7		272.2
Liabilities and Shareholders’ Equity
Accrued income taxes	(29.6)
Non-current deferred income taxes	(48.4)		(65.4)
Adjustments | BCH Belgium Distribution Contracts Misstatement
Assets
Goodwill and other indefinite-lived intangible assets	10.7		10.2
Liabilities and Shareholders’ Equity
Non-current deferred income taxes	(2.1)		$ (8.7)
Adjustments | Adjustments to Income Taxes Accounted For Under ASC 740
Liabilities and Shareholders’ Equity
Accrued income taxes	$ 113.7