Share-Based Compensation: (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Non-qualified stock options	Mar. 31, 2013 Stock options	Mar. 31, 2013 2007 Plan Stock options	Mar. 31, 2013 Predecessor Plan 1998 Directors' Plan Stock options	Dec. 31, 2012 Predecessor Plan 1998 Directors' Plan Stock options	Mar. 31, 2013 Predecessor Plans 1998 Plan Stock options	Dec. 31, 2012 Predecessor Plans 1998 Plan Stock options
Activity in the entity's stock option plans
Outstanding, beginning of period (in shares)		1,353	954	146	146	253	253
Granted (in shares)	0
Exercised (in shares)		(25)	(25)
Forfeited and expired (in shares)		(3)	(3)
Outstanding, end of period (in shares)		1,325	926	146	146	253	253
Exercisable (in shares)		1,121	722	146		253
Weighted average exercise price
Outstanding, weighted average exercise price, beginning of period (in dollars per share)		$ 21.15
Granted, weighted average exercise price (in dollars per share)		$ 0.00
Exercised, weighted average exercise price (in dollars per share)		$ 16.40
Forfeited and expired, weighted average exercise price (in dollars per share)		$ 18.96
Outstanding, weighted average exercise price, end of period (in dollars per share)		$ 21.24
Exercisable, weighted average exercise price (in dollars per share)		$ 21.11
Outstanding, weighted average contractual life		5 years 3 months 18 days
Exercisable, weighted average contractual life		4 years 9 months 18 days
Outstanding, aggregate intrinsic value (in dollars)		$ 4,355
Exercisable, aggregate intrinsic value (in dollars)		$ 3,883