Share-Based Compensation - Restricted stock units payable in stock and cash (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Restricted Stock Units Payable in Stock
Number of Shares/Units
Outstanding at beginning of year, nonvested (in shares) | shares	880
Granted | shares	189
Vested | shares	(272)
Outstanding at end of year, nonvested (in shares) | shares	797
Weighted-Average Grant Date Fair Value
Outstanding at beginning of year, nonvested (in dollars per share) | $ / shares	$ 33.97
Granted | $ / shares	34.50
Vested | $ / shares	(28.57)
Outstanding at end of year, nonvested (in dollars per share) | $ / shares	$ 35.94
Restricted Stock Units Payable in Cash
Number of Shares/Units
Outstanding at beginning of year, nonvested (in shares) | shares	1,492
Granted | shares	403
Vested | shares	(352)
Forfeited | shares	(99)
Outstanding at end of year, nonvested (in shares) | shares	1,444
Weighted-Average Grant Date Fair Value
Outstanding at beginning of year, nonvested (in dollars per share) | $ / shares	$ 34.84
Granted | $ / shares	34.59
Vested | $ / shares	(27.70)
Forfeited | $ / shares	(37.42)
Outstanding at end of year, nonvested (in dollars per share) | $ / shares	$ 36.33