Stock Repurchase (Details) - shares	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2018
Equity [Abstract]
Stock repurchase program, number of shares authorized to be repurchased	15,000,000.0
Repurchase of common stock (in shares)	0
Treasury stock, number of shares held	17,738,499	18,205,142