CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends declared (in dollars per share)	$ 0.27	$ 0.25	$ 0.52	$ 0.5	$ 1.00