Accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Jul. 02, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Outstanding checks in excess of cash	$ 10,044	$ 14,023
Accounts payable, trade	782,051	696,974
Accrued expenses	314,358	293,867
Product warranties	36,754	35,516
Accrued interest	15,011	34,623
Accrued compensation and benefits	175,932	181,022
Total accounts payable and accrued expenses	$ 1,334,150	$ 1,256,025