Share-Based Payment - Plan Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Options
Outstanding at beginning of period (in shares)	1,067,995
Granted (in shares)	253,178
Exercised (in shares)	(204,821)
Forfeited (in shares)	(10,000)
Outstanding at end of period (in shares)	1,106,352	1,067,995
Exercisable at end of period (in shares)	532,362
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 15.70
Granted (in dollars per share)	16.72
Exercised (in dollars per share)	26.62
Forfeited (in dollars per share)	13.05
Outstanding at end of period (in dollars per share)	16.30	$ 15.70
Exercisable at end of period (in dollars per share)	$ 15.44
Weighted-Average Remaining Contract Life (Years)
Outstanding at end of period (in years)	7 years 7 months 6 days
Exercisable at end of period (in years)	6 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding at end of period (in dollars)	$ 13,844
Exercisable at end of period (in dollars)	$ 7,120
Restricted Shares
Restricted Shares - Shares
Nonvested at beginning of period (in shares)	866,378
Granted (in shares)	945,826
Vested (in shares)	(474,077)
Forfeited (in shares)	(25,353)
Nonvested at end of period (in shares)	1,312,774	866,378
Restricted Shares - Weighted Average Grant-date Fair Value
Nonvested at beginning of period (in dollars per share)	$ 16.31
Granted (in dollars per share)	21.03	$ 16.60	$ 18.40
Vested (in dollars per share)	15.49
Forfeited (in dollars per share)	17.31
Nonvested at end of period (in dollars per share)	$ 19.99	$ 16.31