Shareholders' Equity - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Apr. 01, 2019	Dec. 31, 2018	Mar. 11, 2016
Stockholders Equity [Line items]
Capital conservation buffer rate		2.50%	2.50%			1.875%
Stock Repurchase Program 1 [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock	3,200,000
Repurchase shares of common stock, value	$ 100.0
Stock Repurchase Program 1 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase							$ 100.0
Repurchase shares of common stock	1,200,000
Repurchase shares of common stock, value	$ 36.9
Stock Repurchase Program 2 [Member]
Stockholders Equity [Line items]
Amount of stock authorized for repurchase					$ 100.0
Stock Repurchase Program 2 [Member] | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock		537,000
Repurchase shares of common stock, value		$ 17.5
Stock Repurchase Program | Common Stock [Member]
Stockholders Equity [Line items]
Repurchase shares of common stock			1,700,000	243,000
Repurchase shares of common stock, value			$ 54.4	$ 7.9