Goodwill and Other Intangible Assets - Schedule of Intangible Assets Acquired (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	$ 127
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	114
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	1
Proprietary Software [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	12
Key Merchant Services, LLC [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	85
Key Merchant Services, LLC [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	85
Key Merchant Services, LLC [Member] | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	0
Key Merchant Services, LLC [Member] | Proprietary Software [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	0
HelloWallet Holdings, LLC [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	12
HelloWallet Holdings, LLC [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	0
HelloWallet Holdings, LLC [Member] | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	0
HelloWallet Holdings, LLC [Member] | Proprietary Software [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	12
Cain Brothers & Company, LLC. [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	30
Cain Brothers & Company, LLC. [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	29
Cain Brothers & Company, LLC. [Member] | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	1
Cain Brothers & Company, LLC. [Member] | Proprietary Software [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired, subject to amortization	$ 0