Share-Based Awards - Stock Option Activity (Details) (2012 Plan, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
2012 Plan
2012 Incentive Compensation Plan [Roll Forward]
Outstanding, January 1, 2014 (in shares)	1,337,300
Exercised (in shares)	(212,700)
Forfeitures and expired (in shares)	0
Outstanding, December 31, 2014 (in shares)	1,124,600
Vested or expected to vest (in shares)	1,113,400
Exercisable (in shares)	1,075,000
Weighted Average Exercise Price [Roll Forward]
Outstanding, January 1, 2014 (in dollars per share)	$ 19.21
Exercised (in dollars per share)	$ 21.13
Forfeited and expired (in dollars per share)	$ 0.00
Outstanding, December 31, 2014 (in dollars per share)	$ 18.84
Vested or expected to vest (in dollars per share)	$ 18.84
Exercisable (in dollars per share)	$ 18.67
Weighted Average Contractual Life [Abstract]
Weighted average contractual life, December 31, 2014	4 years 6 months 12 days
Vested or expected to vest weighted average contractual life (in years)	4 years 6 months 12 days
Weighted average contractual life, exercisable (in years)	4 years 5 months 12 days
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value, December 31, 2014	$ 23,478
Vested and expected to vest aggregate intrinsic value	23,243
Aggregate intrinsic value, exercisable	$ 22,627