Share-Based Compensation to Employees (Summary of Stock Options and Assumptions) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Sep. 30, 2013	Sep. 30, 2012
Share-based compensation to employees
Weighted average grant date fair value	$ 15.45	$ 9.03	$ 7.26	$ 6.39
Stock Options [Member]
Weighted average assumptions
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility (as a percent)	46.00%	38.40%	48.80%	53.60%
Risk-free interest rate (as a percent)	1.91%	1.65%	1.23%	1.00%
Expected term (in years)	5 years 11 months 12 days	5 years 6 months 20 days	5 years 10 months 9 days	5 years 10 months 13 days
Options
Outstanding, beginning of period (in shares)	3,302	3,747	2,448	1,836
Granted (in shares)	631	360	1,086	740
Exercised (in shares)	(124)	(280)	(124)	0
Canceled (in shares)	(62)	(328)	(108)	(128)
Outstanding, end of period (in shares)	3,747	3,499	3,302	2,448
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 14.41	$ 17.68	$ 13.76	$ 13.84
Granted (in dollars per share)	$ 33.75	$ 23.22	$ 15.58	$ 13.48
Exercised (in dollars per share)	$ 13.48	$ 13.15	$ 12.52	$ 0.00
Canceled (in dollars per share)	$ 15.04	$ 23.74	$ 13.59	$ 13.42
Outstanding, end of period (in dollars per share)	$ 17.68	$ 18.14	$ 14.41	$ 13.76