Indemnifications and Guarantees (Details)	3 Months Ended
	Mar. 31, 2018
Material Wholly Owned Domestic Subsidiaries
Guarantees
Percent of capital stock pledged	100.00%
Material Wholly Owned First Tier Foreign Subsidiaries
Guarantees
Percent of capital stock pledged	65.00%
Material Wholly Owned Foreign Subsidiaries And Material Wholly Owned U S Domiciled Foreign Subsidiaries
Guarantees
Percent of capital stock pledged	100.00%