EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended			9 Months Ended
	Aug. 21, 2015	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2013	Sep. 30, 2015	Sep. 30, 2014
Net income attributable to JCG common shareholders
Net income attributable to JCG		$ 19.9	$ 40.9		$ 109.2	$ 107.7
Less: Allocation of earnings to participating restricted stock awards		0.7	1.4		3.9	3.6
Net income attributable to JCG common shareholders		$ 19.2	$ 39.5		$ 105.3	$ 104.1
Basic earnings per share attributable to JCG common shareholders
Weighted average common shares outstanding		179.9	181.4		180.3	183.0
Basic earnings per share (in dollars per share)		$ 0.11	$ 0.22		$ 0.58	$ 0.57
Diluted earnings per share attributable to JCG common shareholders
Weighted average common shares outstanding		179.9	181.4		180.3	183.0
Incremental common shares		6.5	1.4		7.7	1.0
Weighted average diluted common shares outstanding		186.4	182.8		188.0	184.0
Diluted earnings per share (in dollars per share)		$ 0.10	$ 0.22		$ 0.56	$ 0.57
Dividends paid (per share)	$ 0.09	$ 0.09	$ 0.08	$ 0.07	$ 0.26	$ 0.23
Employee stock options
Anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding
Number of anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding			1.8			3.4
Unvested nonparticipating restricted stock and price-vesting units.
Anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding
Number of anti-dilutive securities that have not been included in the calculation of weighted average diluted shares outstanding			0.1			0.1