Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net income	$ 341.3	$ 249.7	$ 154.5
Adjustments to reconcile net income to net cash from operating activities:
Stock-based compensation expense	195.5	194.3	173.1
Charges associated with convertible senior notes	138.4	0.0	70.0
Depreciation	23.5	17.8	15.1
(Accretion) amortization of (discount) premium on investments, net	(26.2)	(18.3)	3.7
Amortization of intangible assets	3.6	3.5	0.5
Changes in fair values of equity investments	37.1	(28.4)	(30.8)
Deferred income taxes	(123.1)	(56.7)	19.1
Other	24.5	(0.2)	1.6
Changes in operating assets and liabilities:
Accounts receivable	(39.8)	(89.3)	(162.2)
Inventory	(19.1)	5.4	(2.6)
Accounts payable and accrued liabilities	29.0	64.3	114.6
Other assets and liabilities, net	10.7	47.8	(17.2)
Cash flows from operating activities	595.4	389.9	339.4
Cash flows from investing activities:
Purchases of available-for-sale debt securities	(1,056.1)	(1,379.9)	(621.2)
Sales and maturities of available-for-sale debt securities	967.5	972.4	511.0
Acquisition of business, net of cash acquired	0.0	0.0	(42.7)
Purchases of equity investments	0.0	(31.3)	(7.7)
Capital expenditures	(38.2)	(28.3)	(16.5)
Cash flows from investing activities	(126.8)	(467.1)	(177.1)
Cash flows from financing activities:
Issuances of common stock under benefit plans	122.1	65.3	44.7
Repurchases of common stock under accelerated buyback agreements	(300.0)	0.0	0.0
Payments associated with convertible senior notes	(308.8)	0.0	(279.0)
Cash flows from financing activities	(486.7)	65.3	(234.3)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.3	(1.3)
Change in cash and cash equivalents and restricted cash	(18.1)	(11.6)	(73.3)
Cash, cash equivalents and restricted cash at beginning of period	259.1	270.7	344.0
Cash, cash equivalents and restricted cash at end of period	241.0	259.1	270.7
Supplemental Disclosure:
Accrued capital expenditures	2.2	2.5	0.7
Right-of-use assets acquired through operating leases	271.6	200.8	0.0
Cash paid for interest	1.6	3.8	6.6
Cash paid for income taxes	$ 217.5	$ 51.5	$ 14.4

Charges Associated With Convertible Senior Notes

No definition available.

Name:	nbix_ChargesAssociatedWithConvertibleSeniorNotes
Namespace Prefix:	nbix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.