Share-Based Compensation Plans - Schedule of activity of stock options and awards of shares and stock units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Beginning Balance	566,774	1,310,697	1,796,377
Weighted Average Price, Beginning Balance (in dollars per share)	$ 24.15	$ 18.12	$ 17.15
Shares, Granted	0	0	0
Weighted Average Price, Granted (in dollars per share)	$ 0.00	$ 0.00	$ 0.00
Shares, Expired	(30,000)	0	0
Weighted Average Price, Expired (in dollars per share)	$ 12.09	$ 0.00	$ 0.00
Shares, Exercised	(230,048)	(743,923)	(485,680)
Weighted Average Price, Exercised (in dollars per share)	$ 26.71	$ 13.52	$ 14.55
Shares, Ending Balance	306,726	566,774	1,310,697
Weighted Average Price, Ending Balance (in dollars per share)	$ 23.42	$ 24.15	$ 18.12
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, Beginning Balance	634,298	610,803	588,907
Weighted Average Price, Beginning Balance (in dollars per share)	$ 34.16	$ 31.17	$ 28.56
Shares, Granted	241,274	176,418	192,617
Weighted Average Price, Granted (in dollars per share)	$ 45.23	$ 43.06	$ 36.26
Shares, Forfeited	(3,587)	(500)	(15,298)
Weighted Average Price, Forfeited (in dollars per share)	$ 29.56	$ 43.76	$ 29.38
Shares, Vested	(266,497)	(152,423)	(155,423)
Weighted Average Price, Vested (in dollars per share)	$ 32.17	$ 32.46	$ 27.77
Shares, Ending Balance	605,488	634,298	610,803
Weighted Average Price, Ending Balance (in dollars per share)	$ 39.47	$ 34.16	$ 31.17