ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS): (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	$ (4,020)	$ 1,390
Other comprehensive income/loss before reclassifications	(1,445)	(25)
Amounts reclassified from accumulated other comprehensive income/loss	2,270	(695)
Net current-period other comprehensive income/loss, net of taxes	825	(720)
Balance at the end of the period	(3,195)	670
Unrealized Gains / Losses on Available-for-Sale Securities
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(374)	(6)
Other comprehensive income/loss before reclassifications	454	3
Amounts reclassified from accumulated other comprehensive income/loss	(3)	5
Net current-period other comprehensive income/loss, net of taxes	451	8
Balance at the end of the period	77	2
Gains / Losses on Derivatives
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(3,646)	1,396
Other comprehensive income/loss before reclassifications	(1,899)	(28)
Amounts reclassified from accumulated other comprehensive income/loss	2,273	(700)
Net current-period other comprehensive income/loss, net of taxes	374	(728)
Balance at the end of the period	$ (3,272)	$ 668