CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends declared (in dollars per share)	$ 0.25	$ 0.25	$ 1.00