Stock-Based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Jan. 01, 2019	Jan. 31, 2018	Dec. 31, 2018 USD ($) $ / shares company stock-based_retirement_plan shares	Dec. 31, 2017	Dec. 31, 2016	May 10, 2012 shares	May 09, 2012 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock units per common share			1
Expected life in years			6 years	6 years	7 years 11 months
Termination service of employee, years			20 years
Stock units converted to common stock ratio			1-to-1
Grant date per share fair value (in dollars per share) | $ / shares			$ 27.48
Share-based Compensation Arrangement by Share-based Payment Award, Black Scholes, Percentage of Cash Offered in Lieu of Shares				50.00%	50.00%
Options Granted On A Discretionary Basis
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years			10 years
Vesting period			3 years
GPSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash payout ratio			50.00%
Performance measurement period			2 years
Base target share award			100,000
Maximum cash payout ratio			100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Share Payout Ratio			50.00%
Deferred Stock Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years			10 years
Vesting period			15 months
Number of shares granted, deferred compensation multiplier			500.00%
Discount to the market price, percentage			20.00%
Time period for receiving plan distributions, max			10 years
Time period for installment distributions, max			10 years
Share-based Compensation Arrangement by Share-based Payment Awards, Discount from Market Price, Acquisition Interval			14 days
Stock-based retirement plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based retirement plans | stock-based_retirement_plan			2
Automatic employer match, percentage			50.00%
Additional employer match upon certain profitability levels, percentage			50.00%
Measurement performance period, years			3 years
Discount market price purchase date, percentage			85.00%
Performance Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Measurement performance period, years		2 years	3 years
Percentage of award intended to pay out in stock			50.00%	65.00%
Percentage of award intended to pay out in cash			50.00%	35.00%
Reserved percentage of award intended to pay out in cash			100.00%	100.00%
Awards based on TSR compared to peer group (as a percent)			50.00%
Awards based upon relative TSR for certain business unit employees (as a percent)			100.00%
Number of companies forming peer group | company			320
Award based on EBIT CAGR (as a percent)			50.00%
Total shares base award			100,000
Grant date per share fair value (in dollars per share) | $ / shares			$ 40.92
Discount Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount to the market price, percentage			85.00%
Measurement performance period, years			1 year
SBP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
ESUP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			5 years
Prior PSU Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved percentage of award intended to pay out in cash				175.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee termination age, years			65 years
Maximum | GPSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			250.00%
Maximum | Stock-based retirement plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SBP participant contribution for stock or other investment purchases			6.00%
ESUP participant contribution for stock or other investment purchases			10.00%
Premium contributions for ESUP participants			17.65%
SBP merged with 401(k), participant contribution (as a percent)			100.00%
Maximum | Performance Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base award percentage of total shareholder return			200.00%	175.00%
Maximum | PGI
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base award percentage of total shareholder return			250.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee termination age, years			55 years
Minimum | GPSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage			0.00%
Minimum | Performance Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base award percentage of total shareholder return			0.00%
Flexible Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares against plan						3	1
Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized cost of non-vested stock | $			$ 12.9
Remaining contractual life			1 year
Subsequent Event | Maximum | Stock-based retirement plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SBP participant contribution for stock or other investment purchases	20.00%