Stock Compensation - Options outstanding and exercisable (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding (in shares)	1,409,881	1,512,756	1,574,572
Exercise price range, minimum (in dollars per share)	$ 9.00	$ 9.00	$ 9.00
Exercise price range, maximum (in dollars per share)	$ 20.93	$ 20.93	$ 18.62
Exercisable (in shares)	1,231,544	1,066,219	1,057,694
Weighted average exercise price (in dollars per share)	$ 13.47	$ 11.58	$ 11.48