Grants and other liabilities (Tables)

3 Months Ended

Mar. 31, 2018

Grants and other liabilities [Abstract]

Grants and other non-current liabilities

	Balance as of March 31,		Balance as of December 31,
	2018		2017
	($ in thousands)
Grants		1,197,683		1,225,877
Other Liabilities		478,516		410,183
Grant and other non-current liabilities		1,676,199		1,636,060