Combined Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on securities, tax	$ 0	$ (2,000,000)	$ 500,000	$ 3,200,000
Reclassification adjustment for unrealized gains on securities, tax	$ 0	$ (3,200,000)	$ (500,000)	$ (4,500,000)