Accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Outstanding checks in excess of cash	$ 7,276	$ 12,269
Accounts payable, trade	859,913	729,415
Accrued expenses	378,640	333,942
Product warranties	44,196	46,347
Accrued interest	13,346	20,396
Accrued compensation and benefits	220,866	193,213
Total accounts payable and accrued expenses	$ 1,524,237	$ 1,335,582