Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of income before income tax

Components of income before income taxes consist of the following:

	Year Ended December 31,
	2019		2018		2017
United States	$	2,011.2	$	2,151.7	$	1,964.7
Foreign	417.9		401.8		113.8
	$	2,429.1	$	2,553.5	$	2,078.5

Schedule of components of income tax expense

Components of income tax expense consist of the following:

	Year Ended December 31,
	2019			2018			2017
Current:
Federal	$	444.6		$	223.7		$	560.3
State	1.9			4.8			(4.1		)
Foreign	(2.6		)	20.6			4.8
Total current tax expense	443.9			249.1			561.0
Deferred:
Federal	(132.0		)	687.6			317.1
State	(1.7		)	(1.9		)	(1.3		)
Foreign	3.1			(825.7		)	3.2
Total deferred tax (benefit) expense	(130.6		)	(140.0		)	319.0
	$	313.3		$	109.1		$	880.0

Schedule of effective income tax rate reconciliation

A reconciliation of the U.S. statutory income tax rate to the Company's effective income tax rate is as follows:

	Year Ended December 31,
	2019		2018		2017
U.S. federal statutory tax rate	21.0	%	21.0	%	35.0	%
Income tax credits	(4.6	)	(2.6	)	(1.3	)
Stock-based compensation	(2.5	)	(2.5	)	(9.0	)
Foreign-derived intangible income deduction	(1.6	)	(1.0	)	—
Taxation of non-U.S. operations	(1.0	)	(1.9	)	0.7
Non-deductible Branded Prescription Drug Fee	0.7		0.6		1.7
Sale of non-inventory related assets between foreign subsidiaries	—		(6.3	)	—
Impact of change in U.S. corporate tax rate (the Act)	—		(2.7	)	15.7
Domestic production activities deduction	—		—		(2.6	)
Other permanent differences	0.9		(0.3	)	2.1
Effective income tax rate	12.9	%	4.3	%	42.3	%

Schedule of deferred tax assets and liabilities

Significant components of the Company's deferred tax assets and liabilities are as follows:

	As of December 31,
	2019			2018
Deferred tax assets:
Deferred compensation	$	519.7		$	458.2
Fixed assets and intangible assets	192.0			107.8
Accrued expenses	75.9			53.3
Deferred revenue	22.0			20.2
Other	—			33.3
Total deferred tax assets	809.6			672.8
Valuation allowance	(7.0		)	—
Deferred tax assets, net of valuation allowance	802.6			672.8
Deferred tax liabilities:
Other	(11.2		)	(2.7		)
Net deferred tax assets	$	791.4		$	670.1

Schedule of unrecognized tax benefits

The following table reconciles the beginning and ending amounts of unrecognized tax benefits. The amount of unrecognized tax benefits that, if settled, would impact the effective tax rate is $210.8 million, $189.5 million, and $146.2 million as of December 31, 2019, 2018, and 2017, respectively.

	2019			2018			2017
Balance as of January 1	$	189.5		$	146.2		$	117.2
Gross increases related to current year tax positions	37.9			51.4			49.0
Gross (decreases) increases related to prior year tax positions	(7.2		)	5.6			(5.6		)
Gross decreases due to settlements and lapse of statutes of limitations	(9.4		)	(13.7		)	(14.4		)
Balance as of December 31	$	210.8		$	189.5		$	146.2