Employee Stock-Based Incentives - RSUs, Employee Stock Options and SARS Activities (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
RSUs
RSU Number of Shares:
Outstanding, January 1 (in shares)	100,568
Granted (in shares)	36,096
Vested (in shares)	(47,709)
Forfeited (in shares)	(3,648)
Outstanding, December 31 (in shares)	85,307	100,568
RSU's Weighted-Average Grant Date Fair Value (in dollars per share):
Outstanding, January 1 (in dollars per share)	$ 47.81
Granted (in dollars per share)	56.31
Vested (in dollars per share)	41.64
Forfeited (in dollars per share)	54.17
Outstanding, December 31 (in dollars per share)	$ 54.60	$ 47.81
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Total fair value of RSUs that vested	$ 2,800,000	$ 3,200,000	$ 2,900,000
Options/SARs
Employee Stock Options and SARs Number of Shares:
Outstanding, January 1 (in shares)	59,195
Granted (in shares)	107
Exercised (in shares)	(14,313)
Forfeited (in shares)	(943)
Canceled (in shares)	(580)
Outstanding, December 31 (in shares)	43,466	59,195
Exercisable, December 31 (in shares)	31,853
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Outstanding, January 1 (in dollars per share)	$ 45.00
Granted (in dollars per share)	64.41
Exercised (in dollars per share)	40.44
Forfeited (in dollars per share)	43.04
Canceled (in dollars per share)	278.93
Outstanding, December 31 (in dollars per share)	43.51	$ 45.00
Exercisable, December 31 (in dollars per share)	$ 43.85
Weighted-average remaining contractual life, Outstanding	4 years 7 months 12 days
Weighted-average remaining contractual life, Exercisable	4 years 12 days
Aggregate intrinsic value, Outstanding	$ 1,109,411
Aggregate intrinsic value, Exercisable	832,929
Weighted average grant date per share of stock options and SARs granted (in dollars per share)			$ 9.58
Stock options
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Total intrinsic value of options exercised	$ 335,000	$ 539,000	$ 507,000