Accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Outstanding checks in excess of cash	$ 11,737	$ 12,269
Accounts payable, trade	871,438	729,415
Accrued expenses	327,595	333,942
Product warranties	45,080	46,347
Accrued interest	15,257	20,396
Accrued compensation and benefits	195,551	193,213
Total accounts payable and accrued expenses	$ 1,466,658	$ 1,335,582