Equity (Narrative) (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Apr. 29, 2016 USD ($) vote / shares $ / shares shares
Class Of Stock [Line Items]
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, par value | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	31,294,669	31,521,398
Common stock, shares outstanding	31,294,669	31,521,398
Common stock, par value | $ / shares	$ 0.0001	$ 0.0001
Contributed capital, in excess of par value of common stock | $	$ 558,498	$ 557,309
Spin-off from CHS [Member]
Class Of Stock [Line Items]
Preferred stock, shares authorized			100,000,000
Preferred stock, par value | $ / shares			$ 0.0001
Common stock, shares authorized			300,000,000
Common stock, shares issued			28,412,054
Common stock, par value | $ / shares			$ 0.0001
Common stock voting description	Holders of the Company’s common stock are entitled to one vote for each share held of record on all matters for which stockholders may vote. Holders of the Company’s common stock do not have cumulative voting rights in the election of directors.
Number of vote | vote / shares			1
Contributed capital, in excess of par value of common stock | $			$ 530,600