Employee Benefit Plans (Cash-Equivalent Stock Awards) (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Cash Equivalent Stock Awards Rsus [Member]
Activity:
Outstanding, beginning of year, shares | shares	1,277,083
Granted, shares | shares	167,438
Additional awards granted due to achievement of performance criteria, shares | shares	0
Forfeited, shares | shares	(21,932)
Fully vested, shares | shares	(581,829)
Outstanding, end of year, shares | shares	840,760
Weighted average grant date fair value:
Outstanding, beginning of year - weighted average grant date fair value | $ / shares	$ 31.94
Granted - weighted average grant date fair value | $ / shares	31.95
Additional awards granted due to achievement of performance criteria - weighted average grant date fair value | $ / shares	0.00
Forfeited - weighted average grant date fair value | $ / shares	(31.81)
Vested - weighted average grant date fair value | $ / shares	(29.14)
Outstanding, end of year - weighted average grant date fair value | $ / shares	$ 33.88
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Vesting period	4 years
Cash Equivalent Stock Awards Performance Based [Member]
Activity:
Outstanding, beginning of year, shares | shares	693,477
Granted, shares | shares	50,183
Additional awards granted due to achievement of performance criteria, shares | shares	37,434
Forfeited, shares | shares	(5,209)
Fully vested, shares | shares	(325,386)
Outstanding, end of year, shares | shares	450,499
Weighted average grant date fair value:
Outstanding, beginning of year - weighted average grant date fair value | $ / shares	$ 33.25
Granted - weighted average grant date fair value | $ / shares	31.95
Additional awards granted due to achievement of performance criteria - weighted average grant date fair value | $ / shares	29.24
Forfeited - weighted average grant date fair value | $ / shares	(34.05)
Vested - weighted average grant date fair value | $ / shares	(29.24)
Outstanding, end of year - weighted average grant date fair value | $ / shares	$ 35.66
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Vesting period	3 years