Description of business, basis of presentation and summary of significant accounting policies - Early Adoption of New Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 28, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Changes in other assets and liabilities, net	$ (34,352)	$ (1,992)	$ 3,857
Net cash flows from operating activities	683,429	651,231	847,540
Net cash (used for) provided by financing activities	(462,433)	(857,791)	464,123
Previously Accounting Method | Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Changes in other assets and liabilities, net	(63,359)	(40,117)	(22,484)
Net cash flows from operating activities	654,422	613,106	821,199
Net settlement of stock for tax withholding and proceeds from stock option exercises	8,655	31,284	26,672
Net cash (used for) provided by financing activities	(433,426)	(819,666)	490,464
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Changes in other assets and liabilities, net	29,007	38,125	26,341
Net cash flows from operating activities	29,007	38,125	26,341
Net settlement of stock for tax withholding and proceeds from stock option exercises	(29,007)	(38,125)	(26,341)
Net cash (used for) provided by financing activities	$ (29,007)	$ (38,125)	$ (26,341)