SHAREHOLDERS' EQUITY (Details)							3 Months Ended				6 Months Ended		12 Months Ended	77 Months Ended
	May 03, 2018 $ / shares	Mar. 07, 2018 $ / shares	Jan. 17, 2017 USD ($) shares	Jul. 14, 2016 USD ($)	Jan. 29, 2016 shares	Dec. 10, 2013 USD ($) shares	Mar. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) senior_executive $ / shares shares	Sep. 30, 2017 $ / shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares	Sep. 30, 2017 $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Jan. 31, 2018 shares	Oct. 02, 2017	Aug. 31, 2016 USD ($)	Aug. 03, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Feb. 27, 2014 USD ($)	Dec. 21, 2009 USD ($)
SHAREHOLDERS' EQUITY (Details) [Line Items]
Common stock, dividends, per share, cash paid (in Dollars per share) | $ / shares							$ 0.07	$ 0.07	$ 0.06	$ 0.06	$ 0.14	$ 0.12	$ 0.24
Common Stock, Dividends, Per Share, Cash Paid, Total Up To Date | $ / shares											$ 0.14
Special dividends declared (in dollars per share) | $ / shares		$ 1.00
Share-based compensation arrangement by share-based payment award, description											Options granted under the Incentive Plan may be either “incentive stock options” or nonqualified stock options, generally expire ten years after the date of grant and are granted at an exercise price of not less than 100% of the fair market value at the date of grant.
Share-based compensation arrangement by share-based payment award, expiration period											10 years
Maximum percentage of exercise price at grand date fair value											100.00%
Stock-based compensation							$ 2,365,000			$ 2,343,000	$ 4,920,000	$ 4,795,000
Shares paid for tax withholding for share based compensation (in Shares) | shares							6,120				197,452
Shares paid for tax withholding for share based compensation, value							$ 114,000				$ 4,446,000
Shares paid for tax withholding for share based compensation, value per share (in Dollars per share) | $ / shares							$ 18.61				$ 22.51
Face amount																	$ 35,092,000		$ 8,000,000	$ 32,280,000
Stock repurchase program, authorized amount						$ 50,000,000												$ 50,000,000
Stock repurchase program, remaining authorized repurchase amount							$ 21,022,000				$ 21,022,000
Stock repurchased during period (in shares) | shares						4,444,444	1,438,239				1,438,239			17,423,093
Stock repurchased during period, value							$ 28,415				$ 28,415			$ 240,036,000
Stock repurchased during period per share (in Dollars per share) | $ / shares							$ 19.76				$ 19.76			$ 13.78
Remaining number of shares authorized to be repurchased | shares						5,555,556,000
Incentive Stock Options [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Number of shares available for grant (in Shares) | shares							1,192,193				1,192,193
2006 Equity Incentive Plan [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Share based compensation arrangement by share based payment award equity instruments other than options additional grants in future (in Shares) | shares							0				0
Restricted Stock and Restricted Stock Units [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Equity instruments other than options, grants in period (in Shares) | shares								1,008,756
Performance Shares [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Award vesting period							3 years	3 years
Equity instruments other than options, grants in period (in Shares) | shares							250,170	480,756
Equity instruments other than options, vested in period, fair value							$ 4,739,000	$ 9,980,000
Equity instruments other than options, grants in period, weighted average grant date fair value (in Dollars per share) | $ / shares							$ 18.94	$ 20.76
Restricted Stock and Performance Shares [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Equity instruments other than options, grants in period (in Shares) | shares								528,000
Minimum [Member] | Restricted Stock [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Award vesting period											3 years
Maximum [Member] | Restricted Stock [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Award vesting period											4 years
Executive Officer [Member] | Restricted Stock [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Award vesting period								4 years
Equity instruments other than options, vested in period, fair value								$ 7,008,000
Equity instruments other than options, grants in period, weighted average grant date fair value (in Dollars per share) | $ / shares								$ 13.27
Number of persons granted shares | senior_executive								2
Award post-vesting holding period								2 years
Executive Officer [Member] | Minimum [Member] | Restricted Stock [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Awards vested in period (in shares) | shares								384,000
Executive Officer [Member] | Maximum [Member] | Restricted Stock [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Awards vested in period (in shares) | shares								528,000
Convert. debt due 2017 [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Face amount																						$ 100,000,000
Debt instrument, interest rate, stated percentage																						4.00%
Senior Notes 2022 [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Face amount																					$ 600,000,000
Debt instrument, interest rate, stated percentage																5.25%					5.25%
Debt conversion, original debt, amount				$ 125,000,000
Convertible Notes 2017 [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Debt conversion, converted instrument, amount			$ 173,855,000							173,855,000
Debt conversion, converted instrument, cash received			125,000,000							$ 125,000,000
Issuance of treasury stock in settlement of convertible debt			$ 48,858,000
Debt conversion, converted instrument, shares issued | shares			1,954,993							1,954,993
Subsequent Event [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Dividends declared, amount per share (in Dollars per share) | $ / shares	$ 0.07
Incentive Plan [Member]
SHAREHOLDERS' EQUITY (Details) [Line Items]
Number of shares authorized for award (in Shares) | shares					3,350,000										1,000,000
New shares issued (in Shares) | shares					600,000