SHARE-BASED COMPENSATION: (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended					12 Months Ended	9 Months Ended				12 Months Ended	9 Months Ended
	Dec. 31, 2013 Stock options	Dec. 31, 2012 Stock options	Dec. 31, 2013 Restricted stock units	Dec. 31, 2012 Restricted stock units	Dec. 31, 2013 Restricted stock units Time-vesting	Mar. 31, 2013 Restricted stock units Time-vesting	Dec. 31, 2013 Restricted stock units Vesting in equal annual increments over four years	Dec. 31, 2013 Restricted stock units Vesting in equal annual increments over two years	Dec. 31, 2013 Restricted stock units Vesting in one year	Dec. 31, 2013 Restricted stock units Performance-based	Mar. 31, 2013 Restricted stock units Performance-based	Dec. 31, 2013 Restricted stock units Vesting based on total shareholder return Minimum	Dec. 31, 2013 Restricted stock units Vesting based on total shareholder return Maximum
Share-based compensation
Share-based compensation expense	$ 1.7	$ 1.4	$ 8.6	$ 7.5
Future share-based compensation expense expected	5.3		21.9
Period for recognition of unrecognized stock-based compensation expense	4 years		4 years
Non-vested restricted stock unit activity
Outstanding at the beginning of the period (in shares)					1,212,286					863,721
Granted (in shares)					488,231		420,084	12,250	55,897	225,515
Vested (in shares)					(470,548)
Forfeited or cancelled (in shares)					(133,565)					(32,774)
Outstanding at the end of the period (in shares)					1,096,404	1,212,286				1,056,462	863,721
Non-vested restricted stock units, Weighted average fair value per share at grant date
Outstanding at the beginning of the period (in dollars per share)					$ 13.99					$ 11.52
Granted (in dollars per share)					$ 23.03					$ 23.63
Vested (in dollars per share)					$ 13.81
Forfeited or cancelled (in dollars per share)					$ 16.32					$ 18.67
Outstanding at the end of the period (in dollars per share)					$ 17.81	$ 13.99				$ 13.88	$ 11.52
Weighted-average remaining contractual term
Weighted-average remaining contractual term at the beginning of the period					2 years 4 months 17 days	2 years 2 months 26 days				1 year 1 month 24 days	1 year 7 months 17 days
Weighted-average remaining contractual term at the end of the period					2 years 4 months 17 days	2 years 2 months 26 days				1 year 1 month 24 days	1 year 7 months 17 days
Restricted Stock Unit Activity - Other disclosures
Pricing model used for share-based compensation arrangement	binomial lattice									Monte Carlo
Aggregate fair value of restricted stock units granted					$ 11.2					$ 5.3
Performance share awards vested (as a percent)												0.00%	200.00%
Award vesting period							4 years	2 years	1 year