Commitments and Contingencies - Narrative (Details)	1 Months Ended	12 Months Ended
	Jan. 31, 2019 lawsuit multinational_bank municipal_pension_fund	Dec. 31, 2014 institution lawsuit
Commitments and Contingencies Disclosure [Abstract]
Number of financial institutions | institution		40
Number of class action lawsuits | lawsuit	2	4
Number of municipal pension funds | municipal_pension_fund	2
Number of multinational banks | multinational_bank	18