Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash dividend per share (in dollars per share)	$ 0.30	$ 0.25	$ 0.21
Repurchases of common stock (in shares)	255,000	449,371	1,152,233