Employee benefit plans - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP stock issued during period (shares)			700,000	800,000	1,000,000
ESPP weighted average purchase price of shares purchased (usd per share)			$ 6.72	$ 5.28	$ 3.42
Unearned stock-based compensation, expected recognition period			1 year 11 months 23 days
Share-based Payment Arrangement, Expense, Tax Benefit	$ 8,600,000	$ 9,000,000	$ 0
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			4.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match			100.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent			100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value			$ 1,500,000	$ 1,500,000	$ 1,700,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent			100.00%
Defined Benefit Plan, Plan Assets, Contributions by Employer			$ 800,000	$ 800,000	$ 1,400,000
Stock Repurchased During Period, Shares			5,967,000
Treasury Stock Acquired, Average Cost Per Share			$ 6.64
Stock Repurchased During Period, Value			$ 39,619,000
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)			5,813,000
Weighted average price of shares granted (usd per share)			$ 7.68	$ 8.83	$ 4.59
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value			$ 30,800,000	$ 28,500,000	$ 23,900,000
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)			604,000
Weighted average price of shares granted (usd per share)			$ 8.70
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value			$ 4,800,000	3,000,000	1,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value			$ 8.70	$ 7.93	$ 4.05
Employee Stock Purchase Plan Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase Price of Common Stock, Percent			85.00%
Stock Options, ESPP and Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned stock-based compensation costs	$ 53,200,000		$ 53,200,000
2014 Equity Incentive Plans [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period			10 years
2014 Equity Incentive Plans [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period			3 years
2014 Equity Incentive Plans [Member] | Minimum [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period			1 year
2014 Equity Incentive Plans [Member] | Minimum [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period			2 years
2014 Equity Incentive Plans [Member] | Maximum [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period			4 years
2014 Equity Incentive Plans [Member] | Maximum [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period			4 years