CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)		6 Months Ended
	Mar. 05, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01		$ 0.01
Preferred Stock, shares authorized		50,000,000		50,000,000
Preferred Stock, shares issued		10,000,000		0
Preferred Stock, shares outstanding		10,000,000		0
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock	6.15%
Series A liquidation preference		$ 250,000,000.0	$ 250,000
Common Stock, issued shares	10,000,000
Series A Preferred Stock
Preferred Stock, par value (in dollars per share)		$ 0.01		$ 0.01
Preferred Stock, shares authorized		50,000,000		50,000,000
Preferred Stock, shares issued		10,000,000		0
Preferred Stock, shares outstanding				0
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock		6.15%
Class A Common Stock
Common Stock, par value (in dollars per share)		$ 0.01		$ 0.01
Common Stock, authorized shares		500,000,000		500,000,000
Common Stock, issued shares		111,666,126		110,949,850
Common Stock, outstanding shares		111,666,126		110,949,850
Class B Non-Voting Common Stock
Common Stock, par value (in dollars per share)		$ 0.01		$ 0.01
Common Stock, authorized shares		10,000,000		10,000,000
Common Stock, issued shares		0		0
Common Stock, outstanding shares		0		0